When I pull slowly up to a light or stop sign in neutral and braking it feels like the grab is uneven. I'm not sure how to describe it any better than that. Like if you had a flat spot on your tire, almost. The tires are in good shape.
It's very minor; I only notice when I have almost stopped.

I replaced my brakes a couple of months ago. Brembo blanks and Hawk HPS pads.

 

Well, did you measure the run-out on your rotors when installing them? If you did, were they within the spec?

I did use Brembo blanks in the past, together with Raybestos pads. I had my mechanic install them and the result was mediocre; they started vibrating within about 9 months.
I subsequently installed PowerStop rotors and Powerstop pads. Did it myself and spent a lot of time checking the runout. All the checking I did wasn't really necessary as the runout was minimal and no rotor repositioning was needed. Two years later, my Powerstops are still braking fine with no trace of vibration whatsoever.

Feel free to draw your own conclusions - I have drawn mine.

 

Warped rotors. That's very soon for that to happen. Maybe they were machined wrong. Unless you have braked really hard in the mean time, they just sound defective. I find it highly unlikely that the pads transferred any material to the rotor, too. Those are excellent pads, btw.

Any way to return the rotors?

Do yourself a favor and do the 6th gen bbk. The larger rotors won't warp and it doesn't cost much more (if any) than buying high quality stock replacement, plus better stopping power.
Or you can get the store pads and just keep returning them if they warp.

You can get a whole set of calipers and rotors (assuming they're in good shape) from a junkyard.

Someone on here is selling a set of calipers for 65 shipped, too.

I just checked and two 6th gen rotors are 55 before tax at advance auto (30% off code).