"American?"

So I was called out in Yoga class as "The American" yesterday. It offended me and I'm wondering why....
It's true I was born in the US and Lived there 45 and 1/2 years. I'm sure I have an accent and look American (whatever that means) maybe even act a little american. But, my point in leaving that behind was to broaden my understanding of the world, and in that pursuit be embraced by whatever culture or country I am in at the time. Is that possible? I guess I would prefer to be called  just a visitor or just not called out at all.