I'm thinking the master/slave cylinder rather than pressure plate. Typically if it were the pressure plate, it would not want to disengage, you'd be grinding gears unless you stuff the pedal into the carpet, and it would just generally be a chore to drive. So, if you don't feel that the clutch bites at the very extremes of pedal travel, I'd probably investigate the hydraulics.
On the other hand, if you do feel that the clutch bites somewhere around the extremes of pedal travel (mine starts to grab around 1/2, and is almost fully engaged by 2/3 up from the floor), a clutch/pressure plate replacement is probably in your future.