McGregor let a long-range shot from opposition left-back Badr El Kaddouri slip through his legs and into his own net at Ibrox yesterday.
It was an uncharacteristic blunder from a player who has been one of the champions' most consistent performers in the last few seasons.
Ultimately, the goalie's clanger, which gave the visitors a 2-1 lead at half-time against the run of play, did not prove costly for the home team. Rangers romped to an emphatic 4-2 victory in the second half to surge four points clear of their city rivals at the top of the SPL table.
And McCoist, who successfully persuaded McGregor to sign a new deal in the summer, does not think the Scotland international will dwell on the mishap in the coming days.
He revealed: "I had no difficulty at all lifting Allan McGregor in the dressing room at half-time in yesterday's game. He is a top class goalkeeper.
"You could argue that Allan's play went a long, long way towards us winning the title last year. He was outstanding for us last season.
"I said to the boys at half-time: 'Maybe we're due Allan a turn here in the second half'. I would have to say the boys returned quite a few favours for Allan."
McCoist added: "Out of all the players, I was especially pleased for Allan yesterday. He doesn't like losing at the best of times, but he really wouldn't have liked losing yesterday after giving away that goal.
"Good goalkeepers maybe do that three or four times in their career. But, as I said, if anybody was due a favour it is Allan McGregor. He has been top class for us and will continue to be top class for us."
McGregor may sit out the Scottish Communities League Cup tie with Falkirk on Wednesday night – Neil Alexander normally features in that competition – and return in the SPL meeting with his former club Dunfermline on Saturday.