Im not sure how to feel

My boyfriend and I just got into an argument over the fact that I wanted him to delete his wcw post which I let slide for 2 days. The problem isn't him doing a wcw (I think) the problem is that it's his ex. My question is that is it cool for boyfriends to post exes as their woman crushes on instagram? Or am I being insecure. Does it make a difference that they live in 2 different states and dated for a week in high school?