Can't reproduce water leak

I had a similar mysterious leak, I would have a wet floor at the foot of the bed and I would check after a rain nothing but a few days later the towel I placed on the floor would be soaked. I checked everything from AC vents to calking on windows and doors and still found nothing. Then I was watching a TV show about homes in Alaska that are air tight need a vent to outside so you can keep condensation from forming well I opened one of the vents whenever the camper sits and I have not had a wet floor since. I guess my camper was too air tight. I still find it hard to believe that was it but for the last two years I have had no wet floor. I still don't know why it would only get wet at the foot of the bed.