I noticed a noise when I turn corners, like something sliding from side to side. I took the headrest off and a small nut fell out. I haven't had time to take the leather cover off to see what it might be. It's something loose inside of it, any ideas? I have a 2013 with 55K on the odometer.

 

So, the rattle noise continues after the nut fell out?

 

The headrest on the passenger side rattled. At first, I thought it was something with the seatbelt..that checked out ok but i still heard the rattle. so i thought it was something loose on the passenger door, that checked out ok. Still heard the rattle, so i thought it was a loose trim under the passenger seat..again checked out ok. I pretty much gave up trying to find the noise. so one day i was cleaning the leather on the rear passenger side, i placed my hand on the front passenger seat to hold my balance and i heard the noise. Tap the seat again and heard it again. EUREKA! Took it to the dealership since my GS is still under warranty and they pretty much said something came loose in the internal mechanics of the headrest and replaced it with a new one.