One of my puppies sleeps standing up!

I'm a bit worried about one of my chocolate labrador puppies who can only go to sleep if he's standing up. He has 5 siblings who all sleep normally but he has to sleep on his hind legs. He doesn't need a special bed or anything because his balance is amazing but I do occasionally wedge him up between two cushions if he's had a late night. Has anybody experienced this before? Is it something he will grow out of?

Here is a video of him sleeping (sorry about the poor quality);

http://www.youtube.com/watch?v=Tm_s6Ub5_rM&p...