Did you have any electrical repairs/modifications done in Indiana? In other words, what changed in Indiana. Did you have any electrical problems on the overnight stays on the way home? I wonder if any connections vibrated loose during the trip home. You may have to start at the incoming shore power plug and work your way through the AC electrical system checking and tightening connections at every point to find the problem. Do you have a cord reel? This has been a reported point of many loose electrical connections.
The refrigerator light on the non-residential (RV) refrigerators is powered by 12 volts DC, not the AC system.
My EMS system has developed a false repeated detection of the AC power line frequency being low - this causes the protection relay to cut off the power until either the false detection goes away, or I bypass the EMS system. If you understand how the interconnected electrical grid works, and the ramifications of massive power feeds being out of phase due to incorrect generated frequency, you would see that the power frequency being wrong from the grid is nearly impossible. Heck, 1 giant alternator will be pulled (like a giant motor) by the rest of the grid if it is slow. This is limited by huge circuit breakers and wiring capacities.