look like this is a very common problem with the clutch. this is the second time it happen to my car. the sad part is that this is nothing new. alot of 350z owners also experience the same problem. Wonder why nissan hasn't fix it by now.
Sticking Clutch? : 350z / 370z Discussion
06 350z Clutch Pedal Gets Stuck halfway up - ZDriver.com
350z Clutch Problems - Page 2 - Nissan Forums: Nissan Forum