Are you kidding me?

So, not 10 minutes ago my 9 1/2 month old up and just decides to crawl. Not saying I'm not proud and all, but where the heck did this come from? She hasn't so much a tried to crawl up to now, and today she sees a toy she wants across the room, and just goes and gets it like she's been doing this for weeks. Finally! (I think she's been practing in her crib at night)