Standing up in the cot

Okay, he's not standing up by himself yet, but yesterday evening after he had been put to bed and was meant to be asleep I walked into his room, because he'd been making "I'm not asleep noises" and found him standing up holding on to the bars of his cot looking at the door. He was so gorgeous, but given he was meant to be asleep I didn't want to make a big fuss and praise him. He did it again a bit later, still not really interested in going to sleep. Oh well, very cute but a little naughty!