As an Italian living in London, with very light skin and blue eyes, I still get this question asked often enough - just because of my accent. Mostly, it's a way to start a conversation. Personally, I also ask the same questions to most English-sounding and looking people - to learn if they're from London or from somewhere else.
I must admit that I find the whole idea of micro-aggressions somewhat suspect, at least as currently posited, since it becomes an apparent necessity for me to second guess everything that anyone says to me for ulterior or questionable motives. As an introvert this degree of "extrospection" sounds utterly exhausting.