You can add me to the list of people who have done this too! During the day we put one of the dog beds in the closet in the master bedroom because they seem to like the "den" effect, and although they can slide open the door with their noses to get in if the door is shut, it doesn't work for them to get out the same way. One day I must have closed the door by mistake without noticing Moosie was in there - and much later I started hearing barking that seemed like it was soooo far away and I finally realized that he had been locked in the closet for hours! I felt horrible but he didn't seem to bothered about it once he got out...