My indoor fireplace will stay on for about 10 minutes and then shuts down, pilot light and all. I had the gas company come out today and they checked everything, disconnected and reconnected the wiring but didn't see anything wrong. The fireplace stayed on for over 30 minutes after they left, then shut down again. What could be causing this. I don't think I should have to restart the pilot light everytime the fireplace shuts off automatically.