Anything

So my fiancé obviously had other girlfriends prior to me. We got engaged in August and are extremely happy. Anywho since we’ve been engaged his ex (the one before me) has started to like every post and comment on everything he posts on his page, even went as far to post a meme on his wall. They don’t talk, he’s made that clear but they are civil. He’s a supervisor and she works for the same company. I finally let him know it makes me feel a little funky she’s been doing that. He didn’t get it but then on Sunday he made a post and then got in the shower and when he came out of the bathroom he said to me “so I don’t know why but she commented on my post again. I would be willing to delete her if it makes you uncomfortable.” I mean I kinda get where she’s Coming from. They broke up and stayed civil she may have always thought she had a chance...but I’m not sure. I told him he’s obviously not doing anything to act like he’s interested or want her attention but being that he’s in a supervisor position I feel like it could be a bad idea for him to delete her. Also I feel like then once she sees he’s on as a supervisor she’s going to start having issues and need his help. Idk I just have a bad feeling about it, am I justified to have these feelings? Should he do anything about it ?