I have no idea if it is, but this same thing happens to me constantly. People outside of my relationship I have to really trust before I want them touching me; it shocks me when they do unexpectedly. It depends on my mood, how sensitive I am that day, or any other number of reasons. This is just what I picked up on. Sometimes I hate being touched, sometimes I love it. Family is about the same. I only accept hugs, etcetera, from certain people in my family.