My baby is growing up!!! :(

So at about 5:00pm today Sam was obviously in need of a quick cat nap.  I tried laying her down but she wasn't having it.  Now we've known she was capable of pulling herself up (because she's done it sitting on the floor with us before) but she's never done it in her crib... until today!  So needless to say, I laid her down, she got back up.  I had a feeling she wouldn't go down so I hid in her room behind her glider and watched.  I watched her wriggle around and play for a while, then I watched her sit up...  she then pulled up onto her knees at the end of her crib!  So of course I know the next step is one of two options: (a) she'll pull herself up to standing and either topple out of her crib over the side or crumble down at the knees like she does and bust her lip or nose or something on the side of the crib.  Or (b) she'll lean over out of the crib from her knees and face plant to the floor below.  Either option not a good one so we were forced to drop her mattress down a few notches!  So sad!  I feel like my little bitty baby girl is growing up!  :(

Surveillance photo of my sneaky sneaky little girl!