Yes that also, it can be a "normal"/medical reason too, most likely actually. So don't confuse it if it is, or choose to be sure of something until you know for sure.
Yup, can't forget the "mundane" explanations. I've just never had this feeling happen before...
I know one other time I had a dream that... well, I don't want to talk about the dream itself, but it felt much like when you pull a scab off and feel the air on an open wound...
Except all along the back of my head.

I recall actually checking there because of
that. The feeling went away after a short while though when I was awake...