Isn't this also a symptom of a clutch saying bye bye. Start looking for an upgraded clutch and flywheel.....and might as well change the CSC.

Not always the case. My clutch was still perfect when I upgraded it for the turbo build and the dealer still replaced my tranny under warranty.

I just had this happen to me yesterday at a track day. I've been running Redline fluids for 4 years now. Mine is a 2009 with 38,000 miles. So I guess I'm out of luck?? All other gears, it shifts fine. Just 5th gear grinds. I didn't miss a shift or anything, did nothing different, just driving hard. I can try changing the transmission fluid again, but I doubt that will help. Any suggestions?

Have you ever changed the fluid? It should have been done at 30,000 miles. It is too late now though. Take it in for warranty to replace it.

So did a search on the forum about noise when shifting to 5th gear and this was close but not quite what I'm experiencing. When I shift into 5th I hear a slight chirp noise that sounds like it is inside the car. No grinding noise and the shifts are smooth. It doesn't happen all the time and I can never seem to replicate the noise right after it happens. The Z is brand new with less than 2,000 miles on it. Any thoughts?

With a new gearbox it is probably not your synchros yet. (That comes later). I'd run the tranny for 5000 break in miles then put in some quality gearbox oil like redline.