I took my car to Prestige because the coolant turned brown.... They flushed the system and replaced the coolant. Not sure if they replaced the tank...but now I have a leak. My overflow tank is at maximum and there is whitle junk coming from the seam on the coolant tank, as well as on the rubber lining and heat shield below it. I didnt think coolant leaks existed on the MC, only the MCS. I guess its offical now, I have had every thing that can go wrong with this car, go wrong.

 

Time to execute on the lemon law, should have kept your first MC all the problems were taken care of.

 

Yes you have a leak it sounds like from the chaulky light brown yellow dried residue around and under your bottle.
The MCS is famous for leaks in the early bottles. I had mine replaced once in June and no more trouble. Your MC bottle is different design so it might be fine to just replace it. See your service manager. Good luck and I hope you do well with the fix- I did.

 

That really sucks ants! I hope to god your cars bad luck is not contagus.