Hi Ryan,
I blew up my clutch, at about 37k. The clutch was removed to fix a rear main seal oil leak by the previous owner. Apparently the mechanic didn't know how to use a torque wrench and took out the clutch, flywheel, starter and both pieces of the aluminum bell housing. The dealer got GM to kick in for a percentage of the repairs. I think I got about $6000 of work done for about $3500. They had to replace the oil pan too, since that had been installed incorrectly.
Anyway I have had the same problem with going into reverse. I just make it a habbit to continue to push on the stick shift while i'm letting the clutch out. This habbit ensures no grinding.
Hope this helps.