Bike stops fine, no noise. I removed the rear pads to inspect them and they had dime size blue spot . It was faint but obvious bluing, like on an exhaust. Pad was shiny. Are they glazed, heat damaged or just going through midlife crises?

I think that bluing on brake components denotes heat stress.  Can't say I've ever heard of or seen blue spots on brake pads.  I'd check out the rear braking system to make sure the caliper isn't sticking, though.

I used to drive myself nuts paying attention to brake noises, colors and textures. The rear brake is a big joke to start with.  I've got nothing else to add. If you stomp on it, and it does something, it's working....

  :  What he said ^

if it doesn't look like this... you are ok...