Stranger photographing my daughter, am I over reacting?

My mother took my daughter out to a museum this morning to give me a break. She has nursery in the afternoon so I just dressed her in her school uniform to give her maximum time with the dinosaurs. My mum came back and told me that an American tourist (woman alone) asked if she could take a picture of my daughter because she was cute in her little uniform. My mum said yes and made sure she was in the picture too. I freaked out because the school name is on my daughters sweater. I told the school what happened and my mother thinks I am freaking for nothing. Am I being too scared by media hype or should I be wary now?