baby daddys!

My boyfriend and I have been TTC for 10 months. Tonight we found out we are pregnant! I took two tests & they both turned positive really fast. This is my boyfriends first child & he's acting really strange. He doesn't want to get excited because "it's too soon to get excited" and he is just acting moody towards me. I'm over the moon happy & he says he is too, but his mood is telling me otherwise. Is this normal? I guess I expected him to be ecstatic and he's not acting happy at all :( any advice/help would be appreciated. 
Oh, and it was both of us working together wanting a baby, I didn't trap him or anything, he's wanted to be a daddy for years. Just had to throw that out there :) for