I would not be offended. It's part of their life, it's the past, you are the present and hopefully the future. If you are secure in your relationship and they are not mooning over those old pics, then it's just memorabilia. You have to pick your battles in any relationship and unnecesary tension over something that trivial is just not worth it to me. If, however they are always pulling the pics out, then there are unresolved issues that need to be addressed. Then there would be reason to discuss it seriously.