Already??

So Courtney lowered Addy's crib a couple of weeks ago and this Tuesday I discovered that she could get to a sitting position on her own when I went in to get her up from her nap and she was sitting in her bed playing.  Courtney had to lower her mattress alllll the way down to the bottom yesterday (it is so low I feel like she's practically sleeping on the floor!)  Mia discovered that she could pull herself up using the side of her crib and she stood up and was banging her hands on the side of the bed!