Thanks for the replies and input one and all.
I thought I had it fixed by re-adjusting the parking brake but the problem happened again today.
I think it was a combination of two things.
Parking brake adjustment and uneven torque in the lug nuts and the new rotor not centering or perhaps a bit out of plumb, if that makes sense.
The symptoms seemed to only appear when the wheel was on the vehicle. I removed both rears this morning and carefully ran all of the lug nuts on finger tight, moving the wheel slightly up and down and left to right as I finger tightened the lug nuts. Then tightened them, lowered the vehicle, and re-tightened all the lug nuts.
Seemed to do the trick....for now.