he's actually mostly 'kneading' KOOL. Cats do this when they find something that reminds them of their mother and then kneading her belly for milk. They do a little tap dance over and over, sometimes drool and can chew on a corner. Usually chenille, wool, or fake fur can make them do this and they purr and zone out usually too.
Ashe has a wool blankie.
Twix has a fleece one.
Destery has a chenille lovey peedow.
Now the hip action? ........hmmm maybe things just felt a little warm and fuzzy down their too.
I had a male cat, neutered, who used to drag my sweaters out of the laundry hamper and take them into the living room and have his way with them. Only my sweaters, never any other part of laundry and only in the living room, usually when guests were there. He apparently liked to have an audience and loved cashmere. The little bastard.