Quick background since I typically type too much shit. 2012 Tacoma Reg Cab, 4x4 - 5spd, 4cyl. 23k miles now.
Clutch squeak started well before 20k but I waited until it was happening almost all the time. Wanted to make sure dealership could replicate, which they did.
They ordered a new master cylinder and clutch pedal (guy said it had side to side play) - seems about right from what I've read on here as far as parts ordered. There was also mention (on here) of the same parts being used so the problem would likely return again.
Got the truck back, it drove so much better. Not a noise to be heard and pedal felt great. That was on Monday, 10/21/13. Three days later I thought I heard a tiny squeak (not the CREAAAK) when going to work, but it was silent before I even got out of my complex parking lot. The next day, a slight chirp-creak for a few shifts after the truck had sat for ~2 hrs. Tonight, a week after repair, I get out of the grocery store and it's worse than ever before. Very difficult to drive the truck and that noise? No way in hell is the radio going to mask that.
Moral of the story - you may not want to waste your time at the dealership. It seems common that they have to order these parts, so expect two trips. Also expect that it'll come back eventually - and consider that it may come back rather quickly with a vengeance.