Water on the passenger's side floor driving me nuts

[edco]

As the subject states, I'm finding my front pass side carpet absolutely drenched from time to time. Some points:

• It does not happen all the time. With all the snow and ice in NJ in Jan, I did not find any wetness on the carpet
• I have had the drains cleaned by an indy AND the dealer, and they found nothing blocking them
• All the windows are closed and up tight
• Today I found it ON TOP of the winter rubber mats so it's not coming from beneath the floor, it's coming from someplace high enough to cause a pool in the grooves of the rubber mats
• Yes - I have searched

That said, any ideas...?

Thank you
ed