"Passing gas" might not have been your fault. Sometimes fucking will sort of pump air into the bottom, sometime quite a lot. One of the guys at the party last night was a great fuck, but we had this problem. I could actually fell the pressure build up in him as we fucked. Every couple of minutes I had to pull out and let him deflate!
I think everyone has experienced the occasional mudslide. Sometimes guys think they are clean, but I just fucked deeper and harder than they had planed on. I remember once having to stop, and after I pulled out, looked down, laughed, and said :"Boy, don't move. I'm coming back with a towel. Daddy really did fuck the shit out of you!"
I've also met guys who would sort of loose control if you hit a certain place deep inside them. One boyfriend used to roll me on my back while I was still half asleep, and mount my morning wood. If he rode it too hard, he would suddenly jump off and go running to the bathroom, where he would spend the next 20 minutes. We had hit "that' spot again...