well, i went to get a second opinion about the brakes. i told the mechanic to pull the pads and look at them, and also to check the wheel bearings while the car was jacked up. he said everything was in excellent condition with my car and couldn't find any problems. he even test drove it for a while.
could it just be the way the pads are? someone else had mentioned to me that the pads may be glazed, hence the weird metal on metal grinding. however, i remember asking the original mechanic after they installed the new pads about the "proper way" to break in the new pads. he said these pads don't need that initial break in period because... something about them being baked in an oven after manufacture, and them not needing the heat...
does that make any sense?
they are semi ceramic pads. i know ceramic pads are supposed to be quieter than metallic.
i guess i will keep listening to the front end to see what happens. the car seems to stop properly and doesn't make the sound 80% of the time.