Are stiff back legs immediately after waking a sign of hip displasia?

I was at the vet the other day during another one of my paranoia trips and I completely forgot to mention this one. My 9 month old lab mix hobbles for a few seconds after I wake him up to go to the bathroom one last time before I go to bed. He does a few stretches and then he seems pretty normal if not still a little on the stiff side. He seems fine normally and it doesn't seem to effect him when he is running although I don't think anything would stop him from running. I'm not going to the vet for another month unless something else comes up so I thought I would give this a shot. Thanks in advance.