Names
I have this weird paranoia about people's names -- I'm always afraid that I'll call someone I don't know all that well by the wrong name, and they'll think I'm a complete flake. This manifests itself especially strongly with my students; I usually pick up most of their names pretty quickly, but I'm extremely hesitant to actually use them. When I hand back labs or quizzes for the first time, I always have this fear that I'll give the wrong one back to somebody and they'll look at me disapprovingly, and even after that goes successfully (as it always has) I still feel wary.

The other day at LBL, I saw one of my former students. I remembered his name immediately (he was one of the more memorable people in the section), but I still didn't actually get around to using it. It's all very silly, I know, but I wish I could break myself of this habit.