There was a light dusting of snow on the deck this afternoon so when I saw Luna in the driveway, I could say "AHA" and prove she had gone through the upper part of the gate. However, no paw prints. So I still don't know how she is getting out. This evening I bribed her with a rawhide bone. It kept her in the yard. Rocket got a bigger one and they were merrily chewing away for over 30 minutes.