We had this same problem with our Pup, just a couple of weeks ago. In fact, I had a discussion thread going for a while, I think it was "My dog has forgotten that she is housebroken." Pup was doing it at least once a day, and it had to stop! We just started watching her very closely - if she went into the other room, one of us got up to follow. If she woke up, we let her out asap. The problem with Pup is that we never caught her in the act - she was very sneaky! I discovered a new spot maybe 4 or five days ago, but it is not the problem it was for a while! We are just trying to get her regimented, and give us a warning if it's an emergency.