Do you constantly think about how others see you?
Like a previous poster, I also felt "watched" when alone as a child, and was constantly monitoring my behavior. I still feel that way sometimes, but I have more of a grasp on reality now, and can convince myself that I am truly alone.
For me, it isn't that I care what strangers think of me--I certainly do not--it's more that I don't want to draw unwanted attention to myself by appearing different. It wasn't until recently that I discovered what behavior was "different"; now that I know, I am overly-aware of myself in social situations.
I tend to notice obscure things about people and/or their behavior, yet I miss out on the person as a whole. I also tend to assume that everyone else does the same thing, and that they will (for example) notice my odd finger movements and ignore everything else about me... but I have discovered, through talking with NT family members, that this isn't necessarily the case.
I think this sort of obsession with body language, et cetera, it bound to occur in many recently-diagnosed on the spectrum. We have finally pinpointed our issues and we want to exercise some control. Perhaps that is what is happening to you; I believe it may be so in my case.
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ASD mama; ASD four-year-old; hilariously questionable one-year old.