My coolant leaks a tiny bit from somwhere under the intake manifold, I think it is the small hose coming out of the cylinder head. Anyways, it lands on the "shelf" of the block and puddles temporarily near where the transmission meets the engine, then gets burned off after the car runs just a few minutes. If you don't look there specifically when it is leaking you'd never notice it except that it leaves a chalky residue on the "shelf".
I'd wait to see if it keeps leaking, it took mine a couple of weeks to stabilize at the "kalt" line after I changed my coolant. I couldn't tell you why though. Maybe I bled it wrong, I'm pretty new at this, but haven't really had any problems since (except for my tiny leak which I can't seem to correct)!