"You're not your usual smiling self today"

I've been getting this a lot lately. Most people think I'm just not feeling well. So, what's the protocol about telling people you have braces? I told several people at work that I was getting braces, but I didn't send out an office-wide email or anything. I just can't smile the same way that I used to. It's either all or nothing now. When I'm talking to people, mostly I've been trying to hide it--trying to speak without opening my mouth so much. Today I was talking to this girl in the office who's been temping here for the last month or so. She asked me whether I was feeling better. So, I finally just told her, "I got braces last week." To my dismay, she said she didn't even notice that there was something wrong with my teeth. Another person who never noticed? I told her that they're really crooked and she said, "Oh, that's funny, I didn't notice them at all." Granted, she's only seen me for the past month and we usually just chat for a few minutes. I mean, everyday for the past 15-20 years I have thought about how awful my teeth are--was it all in in my head? Or maybe I just did a good job at hiding them.