My boy does it from time to time. But generally he isn't deep asleep when he's in that position. And yes, he does it when he's on the arm or on the back of the sofa. I'll try to get a picture of him.
My mom/family had a cat who would do this. Sometimes his front paws showing and his nose tucked onto/into them. I figure it's nice and warm for the face. Others curl up and tuck their face in and cover with tail, some do it this way. Some cats also just faceplant when super tired too. Kabuto is a cute boy!