What surprised me more, however, was the fact that the Dons fans who travelled to Parkhead could be heard over the home support.
I can recall noticing how loud visiting fans were on a few European nights.
But, other than in some Old Firm games, I'm struggling to think of another occasion when a Scottish club's fans have made their presence felt like that, often out-singing the home support.
It's just a pity many of their songs and chants were so abhorrent. In particular, the abuse aimed at Neil Lennon was disgusting, especially after the events of the previous weekend when he was subjected to missiles being thrown at him while he was watching Aberdeen play St Johnstone at Tynecastle.
It's not as though Neil inflamed the situation. If anything, he underplayed the incident at Tynecastle, and he went out of his way to point out a few fans had badly let down a club for which he had a high regard.
Neil did nothing to deserve what happened to him at Tynecastle, and he certainly didn't deserve the abuse he received on Sunday.
He is entitled to wonder why he is a target. As Neil points out, he spent 11 years playing in England without a semblance of trouble.
But since he has come to Scotland, he's had to put up with so much it embarrasses our country.
I hope the Celtic fans who turn up for Sunday's game against St Johnstone show their support for him.
And I hope the players give them something to sing about by playing much better than they did last weekend.
The likes of Leigh Griffiths and Stefan Johansen have to be given the chance to settle in, with a view to the qualifiers in July, and the best way to do that is by starting games.
The remainder of the season is also when the likes of Teemu Pukki, Amido Balde, Derk Boerrigter and Nir Biton have to prove they are good enough to be included in Neil's plans for next season.