If you didn't have the moisture before the mats, I'd remove the mats. That heavy plastic doesn't breath and RVs gather a lot of condensation just from our breathing, cooking and showers.
Go to a carpet store and find some remnants that match are coordinate with your regular flooring. They can easily be removed for cleaning and when they get too dirty just replace them.
Full-timed for 16 Years . . . Back in S&B Again
Traveled 8 yr in a 2004 Newmar Dutch Star 40' Diesel
& 8 yr in a 33' Travel Supreme 5th wheel