Why does my dog rub the top of her snout on the floor after hiding her bone?

Our dog loves to hide rawhide bones. She will eat half, then enter a hiding frenzy which is always fun to watch. After finding a suitable location and dropping the bone (usually in a corner, under some pillows, behind the TV or under the shoe rack), the dog takes a step back and repeatedly drags the top of her snout across the floor while snorting. The dog was an older shelter pet with no backstory and a lot of lovable quirks; a pet DNA test indicated 50% Australian Koolie (which is accurate to her build and facial features) 25% Akita, and 25% generic mongrel (the test was only like fifty bucks so what the heck?)