Clutch Pedal stays on the floor --- but only twice - weeks apart

[RisBMW]

Hi, 7/94 M3, 141K, some upgrades, OEM clutch, TO, flywheel and pivot replaced within the past 10K miles (4 years or so). Braided line added at the same time - All installed by a pro, not me. Pedal has a UUC bushing that's been in there for 20K+. Shifting from 1st to 2nd at about 4500 rpm the clutch pedal stayed on the floor. This happened once a few weeks ago and again today. After it seemed OK and didn't strand me anywhere.

I figured if it is a hydraulic issue it would happen consistently. Any ideas?

[bmwdirtracer]

Look for fluid in the master cylinder rubber boot, and for fluid dripping out of the bellhousing.
If you can't see either, replace the slave first, because it's much easier, and cheaper. If that doesn't do it, it's the master (most likely).
The issue is hydraulic. (And that's good, because you don't have to pull the trans!)