When changes occur slowly, they are very hard to notice.
Example: my clutch had gotten quite stiff to depress the pedal. I didn't really notice until we put a new one in another 5th Gen. HUGE difference. But my clutch still worked flawlessly and I had no issues. I also noticed that the transmission would grind/clunk going into 3rd sometimes, I thought it may have been me or the shifter bushing was wearing out.
Because of the mileage I felt as though it would be good to go through the trans to add the bronze bushing and rear bearing support (great info from CamaroCracka here
http://www.camaro5.com/forums/showthread.php?t=394512). It turns out that the 2013 1LE transmissions already have the rear bearing support.............at least mine did.
Once disassembled, the input shaft was bad at the pilot bearing and the splines that the clutch disks slide on were also bad. that explains the hard pedal.
Additionally both 3rd gear & syncros were bad. That explains the 3rd gear crunch that had developed. the rest of the trans was in great shape. Again, since mine is a 2013 1LE trans, the input shaft did not need to be upgraded to a high nickel piece, the factory input shaft is plenty strong. I did go ahead and do both the Cryogenic Treatment on all internals & REM polishing of 1-6 gears and syncronizers.
Soooooo, rebuilt trans, new clutch/slave & throwout bearing. While there, I noticed a slight leak from the top of the engine rear cover and that the pilot bearing was rough. Replaced those too!