What the clutch?!?

[Effieman]

This morning it was only about 30 degrees out. The truck had been sitting for about 15 hours....
When I went to leave the parking spot, the clutch grabbed immediately upon letting the pedal out. Pushed the clutch back in quick enough that the engine didn't stall. Did the same thing the second time (grabbed immediately), but was able to engage smoothly. Got to the road (500+ ft) and then everything was normal again.
What could cause something like this to happen?

 

[SenorNoob]

Check your clutch fluid level. I bet it's low now. I had one that clutch didn't work when it got cold. The seals in the slave cylinder shrunk enough to leak under pressure.