It's this vent Sparky. One on the drivers side and one on the passengers side. https://www.ebay.com/itm/For-Nissan...12525951230?_trkparms=aid=1110001&algo=SPLICEThe defroster vent just in front the windshield? That would be difficult to remedy. Or are we talking about the driver/passenger and dual center vents. I would not be too fond of having a dealer "Tech" working on this as I like to do as much of my own maintenance as possible. BUT you need to document the issue w/the dealer as long as the car is under warranty. (12 month?) Has the changing weather have anything to w/this. My bones do sure creak more in winter and the passing yrs! I sure hope you get this fixed as I surely wouldn't want to hear this especially on a relatively new car.