Strange Leak?

[green98]

Hi all, I recently noticed a strange leak on my 1998 Chevy Malibu (3100 sfi) 180,000 mi, it is around the last bolt on the front exhaust manifold near the water pump, it has been very cold for the last week or so (-20 at night) and I think that this might have something to do with the leak. I called my uncle who I bought the car from and he said that a few years ago he noticed this exact problem and it went away after the engine warmed up, and he could never get it to replicate the problem. So I let the engine warm up and sure enough it stopped and now I cant replicate the problem. I should add that while it is leaking, the engine appears to run fine, also what ever it is that its leaking is hitting the exhaust manifold and turning to steam. I have had the car for two years and it doesn't appear to lose oil or coolant, nor dose the oil appear to be contaminated with coolant.

I am wondering if anyone else has a similar problem and can tell me what is causing it, and if its something that I should be concerned with.