I installed akebono pro act pads and centric 120 rotors on the rear of a 2012 accord about 6 months ago. They have around 4-5k miles and I just noticed this streak the other day on the right rear (RR) rotor.

The left rear is streak free. Is this something to be concerned about?

I also noticed an audible sound when braking in reverse only - coming from rear pads/rotors. Applying brakes in Drive has no sound whatsoever - completely quiet. The Reverse braking sound is like I can hear the pad contacting the centric rotor (which had a cross hatch pattern to help with bedding). Photos show the cross hatch pattern isn't completely wore down on the rear centric rotors yet.

The front pads and rotors were replaced with Akebono pads and Wagner rotors (black painted hat) with a smooth face and they are quiet when braking in Drive and Reverse

rear rotor 2

rear rotor 1