Just smile and tell them that no electrons were killed for the sake of your pictures.
Valerie, I would have used the old Charlie Chan quote to the student, "Confucious say, Better not speak and appear dumb then speak and remove all doubt."
BTW, I seldom use my cell phone. I don't twitter or tweet -- birds twitter. People who use facebook seriously need to get a real life. I do like some technology; I have a laptop and a kindle which I love.