Just a tip to name the thread something that is descriptive to your question, rather than your user name. In this case, instead of titling this as Maryebligh, you could have titled it as Unexpected rust on 2104S, or something similar.
Every time you use an apostrophe to make a word plural, a puppy dies.
RV: 2018 Rockwood Mini Lite 2504S
TV: 2019 F-350 Lariat 4WD CCSB 6.7 PSD 3.55, 3,591 lb payload
Former RV: 2007 Fleetwood/Coleman Utah
Former TV: 2005 F-150 King Ranch 4WD SCrew 5.4L Tow Package