I too have had this exact problem. I started this Labor Day weekend when I was coming back from Mexico. It rained really hard from Oklahoma City all the way in to Illinois. Then a week later it rain hard as I was on the express way and again it took in water.
Most of the water was under the rug. I wonder if it came from under the car, door seals, or even from the trunk lid because under the back seats it was damp. My cousin also took in water in his car during the road trip, he blame the air conditioning console in the back.
I used under-coat paint under the car a few weeks ago, but it has felt wet again. This past Friday it rain, but not really hard so I guess I have to wait for another down pour to really see if it happens again. Oh yeah I resealed the screw on the rear spoiler using plummer putting.
If anyone has also had this problem let us know