Hi Brook and welcome.
Just recently my dog has been going on the couch too........I can always tell because she knocks the pillows off, etc.
Sometimes she will even run into the living room while we are there and jump up there and roll around, then off again (just long enough to mess it up).
We let her on the bed for awhile before we go to sleep (I know that's a no-no to Carrie.....!), so maybe we can't expect her to know the difference.