Does he think I dont like dark skin?

My husband is black, and I am white. He knows I've dated black men in the past and we've talked about kids and them being mixed and all that it intells. We just welcomed fraternal twins in March. One is much lighter than the other. He typically comments on their skin tone more than I do. He constantly says the lighter one has gotten way darker, and I say I don't see it. The first thing he says back is almost always, "is it because you don't want to see it?" One time I commented that the lighter twin finally seems a little darker to me, and he asks "is that a bad thing?" And he's asked the exact same question a couple times when I've said the darker twin is almost his same shade of skin. Am I saying something insensitive without realizing it? Is there a response I should give in particular to his questions? I always say there is no problem with it, that I'm just noticing the changes, and that our boys are just completely gorgeous. He knows I love them, and I love him, but I'm wondering if he thinks I don't love his skin, or darker skin, despite my telling him I love his skin and our beautiful babies.