Weird looking belly button!

Mary • 20 years old, engaged, mommy to a babygirl born on July 22nd, fur momma to my Yorkie-Poo, Zelda :)
Tonight my fiance pointed out something that I hadn't noticed, or maybe that just happened for the first time tonight.... My belly button looks really weird, like it'd being pulled, which I guess it is... (17 weeks 4 days) When I stand up it looks normal and my belly isn't that big. But, when I lay down my belly pops out and is hard as a rock :) Is it normal to have your belly button change so early?