What are typical signs of a failing slave or clutch master cylinder?

When I had the tranni out, I also replaced the timing cover seals. After reinstalling the opti, I fired the motor up with the tranni out to check for proper installation of the opti.

I wasn't thinking about the slave cyl at this time, and I know my buddy had to press the clutch in to start the car. So the clutch pedal was pressed in when the slave cyl was hanging freely. The GM repair manuals state this as a big no-no.

I am experiencing an intermittent clutch chatter issue when taking off from a stop. Typically happens in hot weather, and am wondering if this could be a sign of a bad master or slave cyl. It seems to do better if I pump the clutch pedal a few times before trying to take off.

Thomas.