Could my friend be a child predator??

I was in a relationship with a 25 year old when I was 17 (17 is legal where I live) and we ended it after a year and stayed friends for 4 years, and now we've been slowly going distant because of his mental health struggles bleeding into my mental health. He hadn't been in a relationship during that time and then he told me he had a girlfriend that was 18 a few months ago, and he is now 29. Is this something I'm overthinking or could it be something serious?

I've been thinking of just ending our friendship over this because I have a young teen sister and I fear for her.