Today one of my students kept looking at me and smiling. What's up with that?

Though this reminds me of myself. I did that so often, my TAs would call on me because they thought I had a question. But in this case, I keep wondering if I have chalk all over my face. Do my students recognize me for the dork that I really am? I think usually if a female student smiles at me, I'm okay with it; it's a nice feeling, but when a male student does that, it weirds me out. For some reason I expect the guys to either have a "I know it all and what the heck are you saying" face or "I really don't care" or their face down on the table napping...