Dads with PPD?

My husband and I have a 2 year old son and a 1 month old son. He tried so hard with our first one, he jumped at every whim. This time around he is only worried about our 2 year old and isn't connecting with our 1 month old at all. He rarely wants to hold him, he gets super frustrated in the middle of the night if it's his turn to feed.. he just isn't connecting with him... is that weird? I don't know what to do? I don't know if its because we had another boy? He acts overly concerned about hurting our 2 year olds feelings that I think he is forgetting about our 1 month old. Any ideas what to do? I'm at a loss. I can tell he just isn't himself.