I've never actually been told that, but sometimes that's how I feel. Especially when I go on websites or Facebook pages about autism and I read stuff like autistic people being mute or sounding like robots, not showing emotions, lacking empathy, being all logic and obsessed with numbers and mechanical stuff.
I remember one person saying I don't look autistic, and someone else asking why I'm able do draw cartoon characters with such detailed expressions if I have trouble reading expressions on real people.
But then I remember what I read about behavior and traits in female aspies, and it was so much like looking into a mirror I know it has to be true.