Our kids' bathroom has two switches (light and exhaust fan) + a GFI outlet with a nightlight in a three gang wall box. If the fan is switched on and then off quickly the GFI will trip. The fan still works after this so I know the fan is not on the load side of the GFI. I doubt I would have ever noticed this but the kids like to play with the switches and thus I usually find the night light off and GFI tripped.