My ex seems crazy?

So I just found out from my mom that my ex tried to friend request her on Facebook. He also texted her a couple of weeks ago asking how she was doing. Idk if it’s just me, but I would never try to contact any of my ex’s parent. I would move on with my life and put the relationship in the past. He was never close to my mom either with is why I think it’s weird he’s trying to contact her. I have him blocked on everything btw. I’ve already been in a new relationship for a year and we’re expecting a baby in January so I don’t understand what he’s trying to do? He doesn’t have me or any of my friends on social media so he doesn’t know I’m pregnant. But I just think this whole situation is weird. Now I’m conflicted if I should tell my boyfriend about it. My ex caused a lot of issues for my boyfriend and I at the beginning of our relationship so I would hate to bring up someone from my past again and start any issues. What should I do?