Yes, you should let her know about about the nude pics. If the shoe was on the other foot, I'm sure you would like to know about your pics.

No- i would just leave the situation alone because the person could accuse you of stalking them or prying and do a search about them and it could turn ignorant and negative. On the other hand , if you want to ask about their views on privacy from another angle"FIRST", and how important is it for them to have nude pics online it could be a different conversation. For instance,If an ex of his posted them for revenge or he himself posted them then you have no place to question anyone's right to do that. No disrespect ladies, but at times I think SOME women feel a need to "KNOW" every instance of a situation can muddle the lines of boundaries and based on the facts your just friends with Benefits only why are you snooping. Men and women steal body pics and re-post them, so since you didn't specify where the pics were and/or was his face/full name attached to them its hard to ascertain the importance whether you should be the one in that position to broach the conversation.