My drivers side floor is usually wet, even in the morning after sitting for a while, from all the rain, slush, and snow. Check it in the summer, and if its dry its ok. If not, then you might have a problem. Its hard to tell in winter, since when its cold outside, and your car is closed, theres not much evaporation.
when i first got my car (actually test drove it) i noticed moisture on the PASSENGER side floor. i figured somoene may have left the door or window cracked (it was rainy season here in FL). so i test drove the car a few days then bought it. after a couple rains i noticed the carpeting was wet again..
took it to the dealer, they had it for almost 2 weeks, but they found the windwhield was leaking! they replaced the carpeting in the car since it was brand new.
dunno if it will help yer situation at all, but that what i had.
Strange thing because I just noticed this weekend that my car has water stains and is damp where the dead pedal should be. I first thought it was just the snow from my shoes over from the winter but it was a dry sunny day and the floor is damp. I think it just a floor dain plug that has fallen out and needs to be replaced. I've got to get my ball joint fixed this week so I will have the shop look into it for me.