While we are on the subject of GFIs, I have one in the garage that randomly trips. Nothing is plugged directly into the outlet but it is the same circuit for the whole garage - garage door opener, air compressor, cordless tool batter charger, and work bench light. There seems to be no rhyme or reason to what causes it to trip. The GFI outlet was replaced with a new outlet and that did not solve the problem. It randomly trips when no power is being used. I think it might be a ghost or gremlin.