Stranger Danger?

I had a strange episode this morning that left me wondering whether there are any guidelines for such events and did I do the right thing?

I was at the grocery store with my LO who was in his pushchair and in his usual boisterous manner was saying Hi to everyone who walked in. He also waved at some people and at one point he reached out for a man's hand who very graciously took it and shook my LO's hand and smiled at him, but this is where things took a turn, the man got out his camera phone to take a photo of my LO and I, upon seeing that, took a step forward and politely, while smiling, asked him not to take photos. He seemed surprised but put his camera away without any issues.

A lady who saw the entire thing told me 'You did right. I'd have done the same thing.' I told her that I didn't know who the man was and although he might have been the nicest person on earth, I had no way of knowing, to which she agreed.

I'm very wary because I know that there is an Internet underworld and kids are their currency of choice. It might seem overdramatic and I'm quite certain that the man in question wasn't part of any shady organisation (he'd have been very brazen if he was!), but we're living in a world where you just can't take chances.

What's your opinion on the matter? Would you have allowed a stranger to take a photo of your LO?