Good catch; that was probably it, since the seats were dry I know it wasn't an open window/door or sunroof. Similar to the problem on the Impalas with the leaky passenger seat and a bad seal where the filter is.

I tore the carpet out in pieces instead of the "nice way" so I have to replace it anyway. Not a big deal though. I have a few other parts to order from Ed Morad, so I might check with him for the carpet.