Found pictures on BF's phone...

This morning I was looking for a certain picture that he took in my boyfriend's phone. (i know...I know... - and no he didn't know I looked in his phone). But I saw a bunch of pictures of some other girl - nasty pictures... I'm pretty sure they aren't new pictures, but just recently saved to his photo gallery when he got a new phone. My question is should I say something to him? I mean, I looked in his phone when I shouldn't have, so my bad. But why take the time to move over pics of some ex?