Am I the only one that values the little things in a relationship?

So the title isn't really matching but however, few hours ago, I was in school, during the break I met my girlfriend and we were then sitting there and then she just stood up and walked away without saying anything and I felt that I got kinda mad about it because I think it's just a thing of respect to just say goodbye or something like that... But it's also pretty unneccesary to be mad about such little details... Did you ever experience something similar and is that a reason to feel kinda upset or sth like that?