Don't worry about it. Sleep on it and it probably won't be that big of a deal tomorrow. If he really doesn't see his friend that often I could see why he might go out two nights in a row, especially if it's a four day weekend. Everyone is human and we have moods. Maybe he looked past the fact that he really didn't want to go out for the sake of his friend. You really don't know and until you do there's no sense in getting worked up over it.