In my 2012 Advance/Ent, I've successfully paired an iPhone 4 and 4s, both running the latest iOS5 release and have had no problems with phone or music function in either Bluetooth or thru USB.
Perhaps try deleting the phone and try again.
2012 MDX Advance/Entertainment
Black roof rails & Crossbars, Body side molding, Tow package, All season mats, Tri-fold cargo tray, Cargo net, Rear bumper applique
CREE LED Reverse lights, LED License Plate lights, Tailgate lights, Puddle lights, Front Markers, Glove box light, Footwell lights.