James vs. the crib

I was in the boys room helping Anthony clean his room because I need to put the crib mattress down lower for James. James has been pulling himself up to his knees for a couple of days now and I don't want him falling out of the crib. I was sitting on the floor putting Thomas trains away I looked up to see James standing up in his crib. As I started to stand up to get him, he let go of the crib with his arms up and squealed with delight at his new found skill. Before I got there he fell head first into the crib rail. He was now very upset at his crib. After calming him down, I put him back in the crib. He laid there for a long time as I cleaned the floor. Then he was up on his knees biting the crib rail while grunting and making all sorts of noise. I thought it was very cute that he was "getting back" at the crib for hurting him.
He was very proud of himself as I was giving him his lunch.