I made the point that it was only some people who responded that way, and that it seemed to have happened to me mainly (only?) since moving to this part of the world, but I guess you didn't notice. *pats head*
Re the Canadian thing: I'm a Canadian living in the UK. I don't mind at all if people say "you're American, right?" What I do mind is if they disbelieve me and imply that I'm lying when I say that I'm Canadian. Otherwise it's all good.