Pedal may have been just a tad too low in the first place. Also the length of throw with the stock hydraulics is abysmal. Until I fixed that, I was always misjudging the engagement and slipping the shit out of the clutch in second.
@
civicdrivr is on point. I've also had chatter from a blown rear main seal. Got lucky that time. Cleaned up nicely and drove on the same clutch until I bought the FR-S.