Thank you, all, for the replies. Yeah, I have checked all the footwells inside the car and they are dry, including the paper I have placed under the mats to detect moisture .

The first time they put in the green stuff was when my upper radiator hose blew out and started to leak coolant. Thinking that since this is a M-B shop they would automatically add M-B coolant. They didn't and I had to buy my own M-B coolant and had them change the coolant at no charge. Fair enough. Then my upper radiator plastic neck busted and I had to get a new radiator. This time I explicitly told them M-B coolant is to be put in. I really don't know if they even put in M-B coolant as the resevoir appeared greenish when I checked it after the radiator job. I didn't make a big fuss over it because the shop gave me a decent deal on an OEM radiator. And now with this (what appears to be a) leak and seeing the GREEN stuff, and then reading what you guys had to say about this issue, I'm a bit annoyed. Grrrrr. I've given them some shiny pennies, and they know how much I care about my car. Am I being played for a fool?

Thanks again!