I think daddy might be gender-disappointed...

Hi guys! Had my 20 weeks anatomy scan this morning and we found it is a beautiful healthy boy!!! I was shocked because we were already talking about the baby as a she. I think i'm just a bit scared because I have no experience with boys (have a very small family with 1 younger sis). Ive always think girls are easier. My hubby does have a 15 year old boy from a previous relationship, but he was extatic about having a little daddy's girl. He said he was happy as long as the baby is healthy, but I know him well enough to sense he was a little disappointed... I feel bad and I dont know what to do... Don't get me wrong he will be an incredible father - he already is considering the situation with his ex - but IDK maybe I'm projecting...