OK, I just got into my motor home to check the mattress, and yes it seemed damp. The memory foam always seemed like it was damp anyway, but there was a towel under the memory foam and it was damp.
I went over to the grocery store where I shop and borrowed 4 of the plastic containers that their bread is delivered in. Actually I got 6 but only needed 4. They hold the topper up about 4 inches and should allow air to circulate under and through it.
When warmer drier weather comes, I intend to put a pedestal fan in and give it a good drying out.
As we all know (or at least should) MOLD affects a lot of people. Some that don't even know that it is hidden mold that is causing their problems. I am in the Real Estate business and have talked many people out of buying homes with even minor mold problems. Unfortunately many people think that they can get rid of mold with chlorine bleach. A mold remediation guy told me that this is an old wife's tale. Mold is a serious issue and unfortunately, bleach is not the cure-all that many people think it is!
I found this site that can point anyone needing mold remediation to for help.
Best Mold Removal - Kill Mold Naturally
And hopefully these memory foam toppers won't create these issues. Since they are relatively new to the market, I won't be shocked to find that they can cause problems in the future. But we love ours and will take every precaution not to develop mold.