Perhaps after the factory winterized the unit, the technician returned the WH control back to the normal use position. This errors on the safe side and could prevent the owner from filling the system with fresh water and forgetting to return a winterized and by passed WH back to the NORMAL operating position.
If this was done, it is possible that some line bleed of pink RV AF will flow into the WH.
As mentioned before, remove WH drain plug and remove any contamination. If possible rinse out with garden hose. Amazon has nozzle for this purpose.
Water Heater rinse toolLakeside