That's lucky you only had ratting noise from the back seat. For my Q30, picked up 4 months ago brand new, I have ratting noise on Audio Panel, B Pillar and rooftop. Perhaps I will list what I have to dealt with the Infiniti dealership since 4 months ago below.
1. March, 2018 - the steering wheel has adjusted due to it leans a bit toward right when going a straight road. After adjustment done, now it lean left........ Then the Intouch system goes blank sometimes, I mean nothing even shown when parking my car backward......... Then all ratting noise getting worse after picked up the car from dealership
2. April, 2018 - Service Center called, a new Intouch system has arrived, so I took my car there and also asked them to fix the ratting noise. Intouch system is fine till now, no problem, B pillar noise disappeared but there is still noise from the audio panel and rooftop. Then the washer jet not working after I picked up the car.
3. It has been more than a month, they still haven't had the jet pump ready......