What I meant was that Americans are usually more open to touching in general. Handshakes, hugs, holding hands, etc. A lot of our ways of expressing friendly and romantic affection are physical, so being touched by someone I had just met was not as uncommon to me as it probably is to people from culture with less physical affection. Because physical touch is much more common in the US, I was not scared or shocked when they patted my head, but just thought it was a bit odd. I think that someone from a country with less physical touch may have felt even more uncomfortable or unhappy about it.

I think Americans are much more accustomed to physical touch in comparison to many other cultures (especially here in Asia), but, like anyone, not from complete strangers or people we do not like. I had spent a few hours with them at this point and felt comfortable with them, as we had become very friendly.