I agree you likely need to re-grease the backs
with regards to the "glazing, but plenty of pad left", before I did anything I'd try re-bedding the pads.
FIRST, since you don't know the history and bedding requires some hard near stops, bleed the brakes, using DOT4 fluid (NOT dot5).
To re-bed, see: http://www.zeckhausen.com/bedding_in_brakes.htm
Step 4, cool-down, is critical. If you stop all the way or get stuck in traffic, especially after the last effort, you'll likely warp the rotors.
If you're not comfortable doing this procedure, DON'T! Find a track guy to do it for you.