Mines the same. Completely random in my case. Hard and notchy one moment, just heavy but no notchyness the next. I've asked here before but nobody seems to have any real idea other than "the clutch is on the way out". This might be true but to me it doesn't feel like the clutch itself, more like something in the hydraulics. It actually feels as if a piston in one of the hydraulic cylinders is binding slightly possibly due to crap in the fluid catching in the seals. There is also a hydraulic damper in the system which, when you look at how it works, might also cause problems with the pedal feel.
I'm going to bleed the hydraulics and see if new fluid helps things (clutch hydraulics never seem to get flushed like brakes do). It might flush out any crap that's built up in the cylinders and make them smoother, worth a try. I'm also tempted to remove the damper since it's only there to stop engine vibration transmitting back to the clutch pedal to make it feel "nicer". Other people have done the same and reckoned it improved things.