I believe @SlingRider mentioned to me that there was water in the fuse box when he first opened it which could definitely cause the problem! Each fuse has its own small "compartment" explaining how water could get in the top fuse area and not the bottom.
How it got in a "sealed" fuse box... I don't know! If the dealer gives him crap, I will put another 50 amp fuse line to correct the problem.