I need some help here...

Do you have a short shifter?
I'll throw it into 3rd as low as 1800 or as high as 6500 rpm and anywhere in between

The clutch doesn't have a cable, its hydraulic, so you can rule that out, it kind of sounds like a synchronizer going bad, but if it is, its the first one I've heard of on an S197.

Im not familiar with the newer models,but could it have to do with the position of the short shifter?

Sounds suspiciously like a synchro ring, but without actually driving it.... one can only guess.

If it only happens on one gear, that is a classic synchro symptom.

I generally shift between 2800 & 3200 under typical driving conditions...How many miles are on the car? I am guessing either it's a synchro going out as others have suggested or you are just in need of a transmission flush.

I would start with the flushing the transmission & see if that improves the shifting quality any because I've flushed mine twice in 70K miles w/ RP and I've noticed a tremendous difference each time with new fluid. I do believe the synchros go out pretty regularly on 05-09 GT transmissions though (Tremec 3650 I think), so I wouldn't be surprised if that's the cause. If the fluid hasn't been flushed though, that's a good place to start.