Just had our fourth child and he seems uninterested/uninvolved...

So my husband and I have 3 boys and now we have a baby girl shes a week old today well he also has a daughter from a previous relationship he was 16 when he had her but lost custody and so did his ex so she went up for adoption due to her being very unfit and obviously he wasnt ready to raise a baby alone being a 16 year old boy, well anyways hes been an amazing father to our 3 boys he is always so involved in everything hes even taken care of our boys when they were newborns at night time so I could sleep hes always done this but with her he never wants to do anything I have to keep nagging him and he'll do it but he always has to complain about it and make excuses I've been the one feeding her changing her dressing her just doing everything it's a hassle for him to hold her also I'll ask him to hold her for a sec while I'm trying to do something hell agree then walk her to her rock n play sleeper and place her in it like I couldn't have just done that myself....its ridiculous I dont understand why hes like this with her when hes been so Involved and hands on with our boys...do you think hes taking his past out on her could those feeling be coming up from losing his first daughter ? I'm afraid that hes gonna resent her or feel differently towards her what do I do ? I already brought that up to him and he snapped at me. It's making me feel differently towards him because he wanted her so bad now that shes here hes acting like this I just dont get it.