Grandma

So my grandmother has made a few new friends. One of her new friends frequents the jail on occasion and knowing this doesn't really give me the warm fuzzies when I see him and his family over at her house. They are nice people and my grandma loves their little girls but at the same time she's my grandma and I love her and would have to put a serious hurting on anyone who messed with her. Do you think I'm being overly protective and irrational? He hasn't gone to jail for any violent crimes but still, I just don't think my grandma needs to be hanging out with past prisoners of our fine local correctional facility. I'm debating on speaking with him about it, kind of a "I know who you are and I'm watching you" kind of thing. Am I crazy?