Ex says I'm immature

So my ex and I have been split up for 6 months and we have a 3 month old son and today he told me I was immature. Let me get to it. Earlier today I asked him if he was coming to see our son and he said something came up and I was like okay and he said he doesn't always have the gas to come and get our son or see him (I live 35 minutes from him) and I was like that's an excuse because I can bring him to you. Well on most weekends I do Instacart for some extra cash so I'll take my son to my moms and my ex will pick our son up from there and he said well you're never there when I pick him up so I figured you wouldn't bring him to me (our son) and I was like why do I have to be there for you to pick him up and he said I leave before he picks up our son so I don't have to be around him and he said it's immature. First off he wishes he was that special 🤣 and secondly I don't see how that makes me immature 🤷‍♀️ we're not together I don't need to be there when he's there for our son not me. I don't even talk to him unless it's about our son. I don't know what's wrong with him but man lol do y'all think that makes me immature?