When did this happen?

Not 6 months ago my girl was a baby. Today when we were on one of our adventures I looked into the back seat to see a little girl, sitting upright (I recently discovered the thing can actually sit upright...duh!) in her rocket chair singing and doing the hand gestures to Itsy Bitsy Spider, the Wheels on the Bus and If You're Happy and You Know It. It put a big smile on my face, but at the same time it made me a bit weepy to know they really do grow up too fast.