Clutch Pedal Vibration, warped flywheel?

[clean2g]

I thought I had a similar thread a week ago, but I guess it got deleted, anyway, Drivetrain Mods: ACT 2600 clutch, OEM flywheel (turned and machined), Shep rebuilt tranny. I'm having some sort of vibration in my clutch pedal, and the pedal is like super soft. The clutch itself is not slipping. I checked for leaks everywhere, master, slave, oil.. nothing around the vicinity of the tranny. Someone told me it could be some fluid on the clutch disc and it's making it chatter. I had this exact problem like 2 weeks ago, and I just wiped down everything in my engine bay, and within two days it was perfectly normal again.

After I couldn't find any leaks this morning, I thought I'd just go see what my local mechanic would say. He's saying the flywheel is warped, but I'm not so sure that's the case. Has anyone else know of or have had their OEM flywheel warp with an after market clutch? And why would the clutch pedal be soft if just the flywheel is warped, and the other components fine? I replaced the Master and Slave cylinders about a year ago.. unless one of them has failed internally. Anyone have any ideas?