After reading the brochure that I received when I purchased my new 2013 Landmark in Feb. I noticed the phrase " 12" I-Beam frame with rust prohibitive coating" and I was curious what that means, I ask because my Landmark has never traveled more than 17 miles from me here in central florida, has never been near an ocean, as a matter of fact it has only made 3 trips to Disneyworlds Fort Wilderness ( 17 miles ) but yet if I were to take a pressure washer to my frame the "prohibitive coating" would blow off, leaving rusted metal, is this normal for such a rust prohibitive coating? none of the other 5 RV's that I have owned in the past 6 years experienced any rust let alone the massive amount of rust on the underside of my landmark.