After a half mile, 4 braking efforts and half a dozen fillings later:

 

I'm assuming it didn't look like that before you installed it.

That's really bizarre.

Did both sides do that?

 

Just the one.

$34.55 on Amazon, free delivery with Prime. A few bad reviews because of warped, but overall 4.7 out of 5.0 and an "Amazon's Choice".

Oh well. Replacement here tomorrow, so really just a minor inconvenience.