I hear the 5th gear synchros are nearly invincible.

I have had a few issues where i was locked outta 2nd gear.. I have never had an issue with any other tho...? I wonder if there might be an issue with my 2nd gear syncros

Your car is fine. Just don't do it everyday.

@ImportConvert, has this whine changed any in the last 6 months? I noticed it on my '12 g37 too. As you describe, sounds like a low volume SC noise. Present regardless of the clutch being engaged or not. Present mainly between 2-3K rpm after full warmup. Switching to penzoil ultra 5w30 (from the nissan ester) made no difference.

I have the same noise on my nismo and I heard it on my friends base 370z

I thought it was normal, but it tripped me out when I first got the car, I got mine preowned and when I heard that driving it home, the first thing I did was pop the hood and check if it was supercharged lol.