Moisture under foot mats

Aubrey

We have been spending a couple months living in our 2018 T@B 400 to help out family, and I am finding moisture, almost like suds, under a couple mats we lay on the floor.
We were nearly constant with AC usage during a heatwave and I speculated it was condensation, but now the weather is mild and moist at night and we use the Fantastic Fan. Still moist under the mat.

It has a rubber backing and usually occurs in front of shower door. I am watching to see if shower water may be getting through the curtain but no evidence yet.

Has anyone experienced this problem?
I plan to replace mats with a woven material that will breathe better.