Exterior storage doors discoloration

[CaptT]

I have an Alpine 5th wheel, 2013 model purchased new in 2014. This past fall I've noticed that three out of four outside storage doors have a brownish discoloration showing through the fiberglass. Has anyone else experienced this problem?
We wash our trailer at least every other month and was it twice a year. I can't believe a very expensive, " top of the line" fifth wheel that has only been used a few times a year has an issue this bad after only three and one half years! It looks like water must have leaked behind the laminate and caused the discoloration.
This is my second Keystone fifth wheel, having a Montana before this one. I was close to purchasing another Montana but our salesman said the Alpine is at the same level as the Montana and the price reflected this. They were both the same price but we liked the layout of the Alpine better. It's been one thing after another with this unit !! Tires, leaky roof, I had to replace the kitchen faucet, the gray water tanks leaked into the belly pan, the hydraulic lines weren't tied up properly and a screw pierced one causing the slides not to work and dumping fluid all over the interior of the sealed under belly and the main slide wouldn't come in all the way.
Now this! Does anyone know what this discoloration is and how much it entails in having it fixed???
Thanks for any and all help with this!