Congrats!!! stoked for you.
I found out the same news about my baby about 2 weeks ago, and I had the EXACT SAME THOUGHT AS YOU. My wife said "what do you think about it being a girl", and I just said I dont' care at all one way or another as long as she is healthy... that is all I am praying for. Its funny cuz nearly all of my guy friends said EXACTLY the same thing....
I think its a male / female thing... we get so freaked out of the health and safety of our wife (or GF) and the baby that we really just tune out to everything else... whereas the women gets all these maternal emotions going.....
Anyway, congratulation on the girl!! And remember, as new fathers with new daughters, the single most important job of a father is to make sure his daughter never ends up on the pole.... lots of love and security and make sure that girl has no daddyy-issues growing up!! I dunno about you, but I am nervous as hell cuz I know all guys are dirtbags!!