Magic, who just turned 10, has been groaning when he lays down and as he stretches while laying especially since the cold set in. He doesn't when he gets up or stretches while standing.
On a side note, yesterday, I noticed he was stiff upon getting up especially in his one leg where quite a bit of muscle was removed after he was attacked a few years ago. I'm not sure if he wiped out in the snow yesterday because he was fine in the morning. There's no swelling and he puts weight on the leg and he did the stairs just fine. It just appears to be stiffness.