Hi lemmkins,
I understand how you feel. Overscrutinizing is a form of self-criticism. We look for things to get down on ourselves about. The others at the dinner have moved on and, if they are thinking of it at all, they are probably worried about their own behavior!
We all do the best we can, in the moment. When the moment is gone it's gone. All we have is now. If a situation arises later, say someone comes to you and says you did or said something.. then that is your next moment and you can deal with it then... IF it happens. Until then, it is all imagination at work and there is nothing to deal with, which is relieving to discover. You can let it go!
If there are things you don't feel confident about in social situations you might want to work with your therapist on those things. Prepare yourself for battle, so to speak, so that the next time you will go in armed with lots of new skills!
ECHOES