This happens all time with refs.
To Sirmons this is just another game for him, just like the last one he called. Officials don't dwell on games like the fans do. They know themselves when they miss a call or get it right. You can't officiate games and let the fans get in your head. I doubt very much that he is doubting his call in the SC game and has probably forgot about it by now.
It is the nature of the job for fans to be upset about some calls, because they are bias and the officials know that.
So to say they realize they have to be on their best behavior goes without saying. They know that. I would think the coaches and players has to do the same.