Why would you ask a customer's nationality?

I don't find that strange. If I hear a different accent, I feel the urge to find out that person's origin. Conversely if I know a person's origin and yet they don't have much accent, I also compliment them. Overall it's because I am bored most of the time, that's why I do this to people. I suppose she must be bored too sitting at that counter all day doing similar things again and again. I don't think just asking for your nationality means she likes or dislikes you.