professional drivers flash headlights to a passing unit to signal when they are clear to change back into your lane, and all appears safe with their unit.
Should you see a problem with their unit, such as a low tire, loose tie downs, or any other safety hazard, repeated headlight flashes are customary until he acknowledges your signal with appropriate emergency flashers or turn signals that he will investigate your warning.
Please be an advocate, not a dissident of courtesy. As an rver you have joined the ranks of Big Rigs on the highways.