My largest cat has started a strange ritual before lying down on my bed. He'll knead the bedding with both his front and hind legs with his back sort of arched... and he'll do this for a long time before he finally settles in. He just started doing this a couple of weeks ago. He does not "knead" me or do any of that other kitten-y type of behavior (he's four years old). Anyone else's cat do this?