It was just a few minutes after the draw had been made for this season's Champions League group games, and the Celtic manager was holding court in the dressing room at Lennoxtown seconded for conferences with the written Press.
What had so grabbed the manager's attention was the suggestion that, while their home record in the competition should bank them the usual nine points, was it more important than ever they start to improve their notorious away record to give them a chance of progressing to the last 16?
Lennon's reaction was a withering look, and a polite suggestion that yours truly did not get ahead of himself, given that a certain Barcelona were one of the teams assumed to be ready to surrender three points at Parkhead.
Fast forward to Wednesday night, and a deliriously happy Lennon was celebrating a historic victory over the Champions League favourites.
The irony is that Barca had, indeed, been beaten at Parkhead, but the (naively) predicted clean sweep at home had already been lost, courtesy of an opening match draw with Benfica.
Thankfully, that long-awaited win on the road, a 3-2 victory in Moscow on matchday two, had already cancelled out the damage that draw had done.
Now, with seven points in the bag after four games, Celtic lie in second place, with their fate in their own hands.
Barcelona would have bagged one of the two qualifying places from Group G had they won on Wednesday.
But, thanks to the combination of Celtic's shock win and Benfica defeating Spartak in Lisbon, the situation is completely turned on its head.
In fact, all four teams could still qualify and all four could go out – even Barcelona, if they fail to add to the nine points they secured in their opening three games.
That is not going to happen. But the battle to move into the last 16 with Lionel Messi and Co. is still very much on.
Lennon is right to remind everyone that beating Barca does not guarantee anything – other than a good night out and terrific memories for the supporters.
The expectation level has been raised in tandem with the points tally. But there are two major hurdles to overcome before any celebrations can begin.
On matchday five, a week on Tuesday, a win or a score draw in Lisbon would see Celtic guarantee they will finish ahead of Benfica and book at least Europa League football after Christmas.
If Spartak lose to Barcelona in Moscow that night, they will be unable to catch the Hoops and their final game, at Parkhead on December 5, could be rendered meaningless to the Russians – if you count almost £1million in win bonus money immaterial.
But it is what Celtic can achieve that is filling the mind of Lennon and his players.
They have already made history by grabbing that away win in the group, something not even Gordon Strachan – who set the bar by taking Celtic to the last 16 in consecutive years – could achieve.
Beating Barca has also been done before, when Martin O'Neill was in charge, though this present Catalan incarnation is considered the best they have ever had, albeit they are short of a few first-picks due to injury.
Lennon has already moved the result into his memory and is concentrating his attention on the game in Lisbon, though he insists the SPL matches against St Johnstone and Aberdeen between now and then are the priority.
The cautious tactics deployed against Benfica on matchday one were as much to do with finding out about his own players as they were about sounding out the Portuguese.
In his first Champions League campaign as a manager, Lennon recognised the importance of not trying to run before you find out if you can walk in this rarefied atmosphere.
Given subsequent results and performances, chances are he would be more expansive and ambitious if he was afforded the opportunity again.
But, again, it must be emphasised that nothing has been won, nothing achieved, nothing secured.
"At the end of the day, we haven't done anything yet," cautioned Lennon. "We haven't qualified.
"I told the players you have to judge us at the end of the six games."
The contrast between the man who was fighting for his future this time last year, and the figure who stands proudly as a Champions League manager with a team which can compete at this level, is as stark as it is uplifting.
Not that Lennon is above appearing just a little star-struck.
Just 45 minutes after his side had handed Messi his first defeat of the season, the little Argentinian superstar was leaving Celtic Park, carefully ushered towards the team bus by the usual entourage of security staff.
On seeing the world's greatest player, Lennon thrust out a hand, praised the still-bemused Messi on his performance and goal, and added his congratulations on the recent arrival of the Barca icon's son, Thiago.
Lennon has much to celebrate himself, having overseen the birth of a legend on Wednesday in the form of a result which every Celtic fan has already taken to their heart.
It would be a massive disappointment if this win did not lead to a last 16 spot, and Lennon is cute enough to understand that his moment of glory could be used as a stick with which to beat him and his players if they do not manage to secure the progress such a victory deserves.
He told his players to seize the moment on Wednesday night. "I said to them, 'This is your moment, and they don't come around very often.
"I told them, 'You have come a long way. This your time, make the most of it'.
"After what had happened in the Nou Camp, I said to them, 'Don't be gallant losers again'."
They were not. Now hanging on to the victory and using it as a launchpad to bigger and better things is the goal.