Is it insecure to feel uneasy about her talking to her ex?

I don’t have any evidence or proof that anything is going on between them. I don’t even have any reason to believe it. But I see her ex interact with her posts all the time on social media. Sometimes she responds sometimes she doesn’t, sometimes she deletes his comments. Maybe I’m just being insecure I guess. It makes me feel a bit uneasy seeing him be the first to like and retweet everything she posts and the first to comment on everything.