I finally had to replace my brake pads at 130K miles, the brake pads I bought like 50K miles ago in anticipation of replacement.
The "squeaker" finally went off but I wasn't sure which one, pulled the front wheels, they still had 70% material left(original pads) wow...Hmmmm. pulled the left rear, 50% left..., pulled the right rear and the outer pad had 50% left but the inner was at the "squeaker"(>10%)...That's odd. just Changed them out(rears only)since 130K is more than acceptable wear for the originals.
I am curious why the rears wore out before the fronts, I guess because the fronts are much larger than the puny rears. I also wonder why only the inner on one wheel wore out, the one with the squeaker. My cynical side almost wants to say the stealership put a worn pad on there a few months ago when they were leaning on me to change the pads for $400!(lol).
I still didn't change the fronts because I just have a hard time discarding pads that have 70% left.
Now that the rear brakes are done, I also gave the entire vehicle the once over including the traction battery cells, I figure I should be good until 200K-250K...knock on wood.

 

Most likely a caliper slide issue causing the pad not to fully retract.

 

My thoughts exactly but I saw nothing out of the ordinary , checked the slides, moved fine, and I had just check the pads less than 6 months/20K miles ago and nothing was amiss. I did re-grease the slides although I saw no evidence that this was necessary.

 

I replaced my pads at 133k miles as well. The inner had more wear than outer which I usually use since it was visible.