My clutch pedal became useless for a little while...

Vbp6US

So I'm leaving work tonight around 630 pm and notice my clutch pedal has a bunch of play all the way down to the floor except for say about 2". Basically no feathering of the clutch at all. I pulled over and turned the car off and back on and still there.

I keep driving to my destination and notice engagement is difficult because it's happening at the very end of the pedal's normal distance (near the floor). I finally reach my destination and as I get off the freeway I notice the clutch is back to normal and that play that existed before is gone. Now I could feel something is happening as soon as I press the clutch and it doesn't flop around.

What are some possible causes for this? I was told there might be air in the fluid some reservoir but I have no idea how that works. I can't seem to reproduce it to show the dealership...anyone ever have this happen to them? My car is stock. No spring mod or anything.

thanks