wearing the wear grooves on the pads away completely is maximum wear, shops will often reccomend replacement once the pad material is half gone, usually because they're nowhere near as efficient as new or near new pads, also, the temperatures generated pass through to the brake fluid much easier degrading performance further. of course, turning a profit wouldn't come into it at all..........
dragonworld is right, the pads will sit against the rotor and rub slightly, as long as they're not binding, which you would notice by the effort required to turn the wheel, all is ok. did you inspect the calipers? were they clean? especially around the pistons as a build up of road grime and brake dust will stop them retracting completely causing the potential binding.
paul.
