Just discovered the same thing!!!
I just discovered the same thing on the driver's side floor well but I haven't checked the passenger side closely. I suspect that could be either the air con drain holes or a leak from somewhere else. I noticed it on Saturday after the heavy rain Friday night but then Friday was a warm day and I did have the air con on for a 7 hour trip. Where can I find the air con drain holes and what is the best way to clean them out? I assume that they must be somewhere on the underside near the firewall/bell housing.
If I still have the problem I'll guess it is a case of keep looking.
