Should I be concerned?

So I’ve been seeing this guy for a few months now. We hang out every weekend and occasionally on the weeks when we aren’t working. He is very charming and nice and funny but he does have a child with another woman. He’s told me the whole story on how horrible she is and how she took his son away and now he’s stuck with limited visitation. She lives in a different state and they do Skype calls every weekend and I always see it too. She seems nice, she’s married, has a home, has a toddler and the child that my boyfriend and her have. She’s very respectful on the video with helping keeping there son interested. But lately there son has been calling me his lasts girlfriends name instead of my real name. The mother corrects him which is nice and my boyfriend tells him that’s not ok but why would a child be doing that should I be alarmed? All he does is talk bad about her they have to use a special parenting app to talk so I never seen the messages.
Should I be concerned?
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