Could I Have Rodents in My Mobile Home?

I have never known mice or rats to make visible "burrows". And I doubt that you would have either with 3 cats. I also think it might be a moisture problem.

Sounds to me like you have a moisture problem. Different kinds of wood products act differently when they absorb moisture. On some, the upper layer of wood starts to ripple. The problem could be caused by moisture under your mobile home, or it could be comming in behind a wall when it rains, then soaking into the floor.

Keep in mind that electrical plugs can come loose after time in a mobile home, in our older home, we found that with some plugs, the screws were applied to the drywall only, not where there were studs, and these eventually wiggled loose.
Yes, you could have a rodent problem. We found out after the bathroom floor caved in from moisture, that a rabbit had somehow gotten under the trailer, and chewed through the hot water line, and made a tiny hole in a water line, which was spraying a fine mist to the underside of my bathroom floor! We knew it was a rabbit as the carcass was still there.