Ugh...coolant leak?

[particlewave]

I spent some time driving in KC on Tuesday during high temps...after parking, I noticed a small river flowing from under the car. It was coolant. Looked to be about a liter or so and had stopped by the time that I noticed it and looked under the car and rear trunk. From the stream, I could tell that it originated from the resevoir/fill tank area.

I'll do some searching, but was hoping for some quick, experienced answers before I tear into things...is this a boil over situation, or am I looking at a leak? No condensation under the trunk and no overheating, though the temp needle was slightly higher than normal.

?????