Unusual Brake Rotor Marks

I swapped my front brakes a few thousand miles ago. New Bosch ceramic pads, Raybestos rotors and new pins. All was well until last week when I noticed shaking in the steering wheel when braking. It came on fairly suddenly. I pulled the wheels off this weekend to check it out and the only issue I can see is the unusual diagonal scratches on the outside of the DS rotor. They only cover about 1/3 of the rotor and the rest looks normal. I assume they are grabbing the pad a little when they come around. I'm perplexed as to what would have caused those kind of markings? They aren't concentric or radial marks. All I can come up with is I got a casting in the rotor. Everything else is tight. All 4 pistons look like they are pushing evenly. Any ideas?