Belle has done this since we got her at 2 pounds. She does it on the couch, in her crate, on her blankets and especially in our bed. Sometimes she will dig to "bury" a toy or biscuit. She gets it just right then uses her nose to pack in down. When she's done she looks at me and once in awhile just to be a pain, I'll say, "I can see it!", then she has to start all over again. Fun to watch
