Leaking Slides

By chance, when you pulled the slides in, did you check the roof of the slides first to make sure there were no sticks, leaves, or even tree droppings like nuts or berries? Small twigs, even leaves can get caught in the rubber seals, allow passage of water. If there was water on the top of the slide when you pulled the slide in, water could have gushed in through those small spaces, drip down the wall, and onto the floor. It does not take much of anything to get caught and keep the rubber from working like a wind shield wiper when the slides are retracted. And then if something is caught in the rubber, if it continues to rain, it will continue to come in.

Another small tip, keep the camper just slightly off level (front to back), so if it rains, water will run off the slide before you retract it.

I only ever had water once in many years with slides. The seal had not extended properly when putting the slide out and I hadn't levelled the trailer (quick overnight stop).
Water backed down the bottom of the slide end and into the trailer. Hasn't happened since.

The only time our slide leaked, we discovered that there is a small rain diversion gutter and unless you tuck the side seal behind it, it will divert the water inside the TT.

Also, as mentioned, if you crawl up and look at the top of the side, you may find lot of stuff up there that rides in and out with the side.

We have never had a leak issue with the slide retracted.