Yeah something like that happened to me as well at work.
It was a client, who usually talked all buddy buddy with me. But one day i pissed him off and he blurted out something offensive to me. Being the sensitive person i am, i was shocked and really took it to heart. It has never been the same since.
The first few days after that he went all buddy buddy with me once again. Eh, but i couldn't really make myself reciprocate/return the favor anymore. To me, he has become a hypocrite person. One who i can never trust again. In the end, he gave up trying to be buddy buddy with me once again. I don't know, i know i should be forgiving and all. But i find it hard to trust that guy again.
Sometimes, I think it's all part of being social though. Trying to act cheerful, and friendly to everyone you meet. Being tactful. Maybe it's one of those social etiquettes everyone needs to know or observe when interacting/socializing with people. I mean you just can't express openly to people what you feel. Especially if it's a negative feeling like anger, contempt, hate, disgust, etc.. For me, i'm guilty of doing this as well. It's not like i like everyone i meet at work. There are a few that do get to my nerves. But i have to be respectful to those persons too. When these bottled feelings accumulate though, its hard to keep all of these emotions in. And some of it will just show in the end.