This also happens to me a lot for some reason ? people always look slightly surprised when I open my mouth and I'm English.Strangely, a lot of people seem to think I'm Spanish and the security guard outright asked me if I had any drugs in my purse (in Spanish) before I played dumb with 'what..?' and the other security guard had to explain to her I was english. Worked as a great diversion for me
I think I should make a positive effort to improve my Spanish for next year ? might come in handy judging by your experience.