I just hit 100k miles and this started. I notice it when I pull in from a drive, or at idle if I Rev it a little bit the noise starts and lasts for about 30 seconds when I go to idle. Here's the link to the video.

https://youtu.be/LoSKlaRUvXQ

Any thoughts?

It's a 2009 G37 S with the 6 speed manual. I pushed the clutch in during the video so you could hear it better over the flywheel chatter. My oil is fine and I change it every 3500 miles.