I'll jump in with Terry and respond to Jeff. Bet there are a lot people who
saw your first post but since it was a few days after a l-e-n-g-t-h-y
disucussion about heads, we passed by without answering?!

I'm not real technical but, IMHO, here's a quick summary of what the deal is
and what you might expect. My head job was done at 77,419 (87 Synchro).
1. The problem is corrosion/pitting on the head surface--some think it's
under the gasket, I think it the surface of the heads where the antifreeze is
in contact and then gradually works under the gasket
2. Cause? Many think its the wrong kind of coolant. VW says to use their
phosphate-free. Some think it's aggravated by not changing coolant every
couple years
3. Cause? Others think that air gets in cooling sys and causes
corrosion--there's certainly potential for air in the system is it's not bled
properly. VW did a head retorquing campaign back in '90 also.
4. Advance detection? In my case, I noticed small amounts of coolant hanging
on the little corner tabs at the corners underneath the block. I had several
months of advance notice. Others have experienced a phenomonon where there
coolant refill tank keeps filling up. This is caused by gases in the engine
escaping into the cooling system and increasing the coolant volume, thereby
pushing the coolant back into the refill tank. Don't know how long this would
happen before a repair should be done.
5.FIX? One the leak has occured you'll need new heads & gaskets resurfaced
heads & new gaskets. I had new heads put on--don't have an intelligent
opinion on resurfaced ones. I'm sure there are others who could tell you.

Sounds like your mileage may not be quite as high as those who have had the
problem, but maybe it's as much a factor of time. If I were you, I'd just
make sure to have fresh(no longer the 2 years) coolant of the non-phosphate
type, make sure the system is bled properly and watch closely for drips on
underside of engine or for increasing levels in refill tank. If the later
happens, I saw a post explaining the you should syphon the excess coolant out
of the refill tank and PUT IT BACK into the expansion tank(the one with the
cap w/tube out the side).

Hope this helps....it may create a whole new bunch of more detailed posts.

Dan