When I was getting to know Erika's Corgi, Bonnie, one of the first things I noticed about her was her tendency to sleep or just lie around on her back with her belly exposed. I don't remember our Golden Retrievers or Hobie, our Rotie/German Shepherd mix doing that very often, if ever.
Yesterday evening, when I watched the sleeping Darby slowing roll off her tummy onto her side, then slowly onto her back, I thought "She knows she's home; she's comfortable here!"
(Last night she slept from 9:00 to 2:45 when her bladder woke her. Back to sleep until 5:05. I can handle that!)