Varying Clutch Pedal Freeplay

Hey, I have looked on the forum before posting this. I haven't seen any posts that talked about varying clutch pedal freeplay.

Ok, when I first start driving the clutch pedal freeplay (the distance when you lightly press the clutch pedal and feel the initial resistance) is totally fine (barely any) after I shift the freeplay gets bigger, and bigger respectively. However, If I don't press the clutch pedal for a while, it slowly returns to how it was when I first started driving. Fortunately, this doesn't sound like a firewall flexing issue, but other clutch pedal freeplay issues are static, not varying.
I have bled and replaced the DOT3 fluid, and it isn't leaking. It must be the master cylinder or something, hopefully not slave.

Any ideas?
Thanks!

I would check the cmc rod where it connects to the pedal, it's a crap plastic bushing that doesn't really hold up to much. If that brakes the rod will start to pop off and wear away the rod and pin, I now use brass bushings for mine, but I have a stage 2