Husband strange behavior

Has anyone else felt they their husbands/partners are acting different lately? Our son is just over 6 weeks old now and at first he was so sweet, supportive and loving and I felt we were so in sync emotionally. Lately he's been more distant with me and has taken a sudden interest in fitness, dieting and improving his wardrobe. He still goes through the motions of helping with chores and things but not with the same attitude as before. He also sleeps on the couch a lot more. I want to chalk all this up to the adjustment of having a newborn and sleep deprivation but I'm starting to feel really insecure. Am I just horomomal??