I think a lot of people with Asperger's syndrome have a similar story: they are walking down the street or through the hallways of school or work, deep in thought about something, and someone asks, "Are you okay?" or comments, "Don't look so sad!" It's frustrating, incredibly frustrating. It takes all my willpower to refrain from answering with a wise remark or from saying something nasty to them.
This has been going on my entire life and while it doesn't bother me too much if people I know ask me what's wrong, it bothers me when total strangers ask me what's wrong or comment on the fact that I don't have a Cheshire Cat grin on my face. A couple months ago, I was heading back to work after my lunch break, and some random woman on the street said, "Aw, don't look so sad!" I just laughed it off but what I really wanted to say was, "And who are you? Do you know me? If something were wrong, do you honestly think that your comment would make me feel better?"
I find myself wondering, too, if people notice more if a girl or woman doesn't smile. Females are expected to be highly social pack animals. I don't know if a study has been made about the frequency of females being reminded to smile, but I do know that a study has inversely linked testosterone levels to frequency of smiling. Males smile less frequently than women on average. That said, what do people think if they see a guy not smiling? Do they think he's just deep in thought? Does the phrase "still waters run deep" come to mind more readily when one sees a non-smiling guy than a non-smiling girl? It's worth thinking about as one of the many double-standards that apply to females vs. males with Asperger's syndrome, as many people with AS are not chronic smilers.