Would you take it as a red flag?

we have only been talking for one day. This was his last message to me. I always find it odd when someone brings up their ex to soon and he just seems to bring her up sometimes. I get that he has kids and it really doesn’t bother me and it doesn’t bother me that he has a relationship with her. In fact I hope he has a great relationship with her but I find it odd to talk about her a lot after only talking to me for one day. I almost feel like he lost that family dynamic and is trying to hurry and get it back with someone else now that he can’t have it with her. Idk maybe he’s just trying to tell me about himself and I’m taking it wrong because I’m cautious with men at this point

Edit: Thanks ladies! I get worried sometimes and always post my online dating life on here for help and you guys always help me and I appreciate it.