Ok, So I'm in denile..

[350SL4spd]

No, not the river...
This hasn't even started to sink in yet.... I was just doing a cap/rotor job on my new 1991 300E and while twisted sideways trying to get the bottom bolt on the cap off I thought my overflow reservoir looked funny...like kinda dark and muddy...oh S#@%!!
This was something that I wasn't concerned w/ at purchase because I had the paper work in my hand of the head having been done less than one year/25k mi ago. And it was all shiny and everything...
So my question is: what happened?!?! Is there something that I can't think of that would be an issue other than the head? There are no leaks visible and the compression is totally top notch. Was the head warped and not planed when the head job was done? It was an indy so I can't complain to the dealer....
I know that I'm probably f%@&ed and that I should clear out a block of three or four days on the calender to deal w/ this, but I'm hoping that there's some less involved thing that could have gone wrong.
Any hope will be greatly appreciated. Any despair will be accepted and quickly followed w/ a round of gin martinis.
Thanks.
-Matt-