I recently learned that there is a whole series of unwritten rules about hugging, rules that in 35 years of life, everyone just assumed that I knew and was purposely not following. This of course was not the case, but one of the bad parts of being autistic is not knowing these unwritten rules and not being able to figure them out on your own.
For me a hug was a hug and all hugs were created equal. I had no understanding of the difference between the "I'm just being polite" hug and the "best friends" hug or even the "I barely know you" hug. To make things worse for me, I'm sensory seeking for touch, so I love to squeese and be squeesed, so being hugged has always been a good feeling.
My fiance gave me a quick tutorial on hugging a few weeks back. She'd realized, as she learned more about autism, that the reason I'd been hugging in what seemed to be a creepy way, was that I didn't know the rules. So now I have the added joy of having to think when someone hugs me, "what kind of hug is this?" and "where is the let go of me sign?" Of course there is an advantage for her, now she's the only one who gets hugs from me that are undistracted by thinking about the rules.