It's the left rear pads that are worn.Simple.
How could I have missed that?
I swear I had inspected ALL the discs (with the wheels on) and didn't see any of 'em being "eaten alive" by the pads (no scoring).
Guess I wasn't looking close enough...but at least the issue i sout of the way for good!
Looking back, it sure sounded like it was coming from the front left wheel though...