Hello and welcome! I suspect it is something she did to her daughter when she was younger. And the mother wants to bring back that bond on some level maybe? As in "Can my sweet baby help out her mama?"

I don't think it's anything to worry a lot over. Remember that to many mothers their children never do grow up. Yes, it can be aggravating. The issue might re-appear later when your daughter wants to be more independent in her marriage and her mother feels threatened--but let's not borrow trouble! Those are my thoughts anyway!