Yeah, no fluid will do that /ubbthreads/images/graemlins/smile.gif I'd keep an eye on the level though, as if it goes down again, you have a leak somewhere and if you have a leak (post slave cylinder), your hydraulic system will not work right (not a closed system)...If it's before the slave cylinder you're probably OK hydraulics-wise, but I imagine that could introduce air in the system, which would also render your hydralic system ineffective.
I'd try to bleed the system if I were you, regardless. I don't know if this oem-equipped, but I have a zerk fitting right by the transmission for bleeding and when the time comes for me, I'll use my mityvac to do it (one man).
This doesn't sound like your problem, but in my GTO I owned, the line from the reservoir to the slave cylinder ran by the exhaust manifold and it would generate a lot of heat when I ran it hard (mostly on the freeway) and would make my pedal go from firm to feeling like there was no pressure and the pedal would go to the floor...a few seconds later, it was back to normal. I didn't realize at the time because of where the line ran, but now know that can be insulated and it gets rid of the issue. I have another GTO now and going to see if it has the same issue (the line seems to route differently on this one).
One other consideration is if your brake (clutch) fluid is contaminated with water, it will boil over chances are and again render your hydraulics not as effective. Water won't compress, but its boiling point is relatively low, so that's why they don't use it as a medium (vs. brake or hydraulic fluid), fwiw.
