Most GFCI receptacles have a wiring option to give GFCI protection to non-GFCI outlets downstream. If there is a ground fault on one of the downstream outlets, the actual GFCI will trip regardless of it's location. A GFCI is required within 6' of a sink (bath or kitchen), outdoors, and a number of other locations that aren't applicable on an RV. The bathroom GFCI on my Monty protects the one on the kitchen island and the outdoor outlet. I'm thinking it's a remote GFCI that's tripped. The fact it's not labeled could well be a mistake in the (lack of) quality control RV manufacturers are practicing now.