Murphy does this too, when we're at training, in the show ring or anywhere where he wants to talk to other people or dogs and not me he will lay like this and then do (what we call) 'The Caterpillar' across the floor to get where he wants to be! He slides on his tum propelled by flailing back and front legs!
A breeder once told me it means that they have good hips like cockers should if they lay like this! So it's definitely not a bad thing. Although if you're that worried a quick vet check can't hurt (except your purse strings!).
