Squeaky Brakes...cause?

Off brand brakes question.....
About a month or so ago I did the brakes on my fiance's 07 saturn ion.
I replaced the front rotors and had the rear drums resurfaced at O'Reiley's (formerly aka Murray's).
Now, the rear drums squeak very loudly when braking. But they only squeak at the very end of the braking. What I mean by that is, when I first step on the brake pedal, there's no abnormal noise. It's at the very end when the car is almost at a complete stop when the rear brakes make the loud squeal.

I've done brakes for decades and have not tun into this.
I tried taking the pads off again and cleaned everything, but they still squeal.
There's still plenty of pad material.

Did I maybe not adjust something properly?
Could it be the pads I purchased?

Anyone have ideas?