the outer brake pads on these vehicels have these little tabs which need to be bent inward after installation to keep the outer pad from shifting whild driving. Your mechanic should be aware of this as it is really common and usually this problem will cuase a noise once when stepping on the brake in forward and will not do it agian until you put it in reverse and hit the brakes.

if your rotors are warped as they say NORMALLY you will also get a lot of shakeing while applying the brakes at highway speeds. Check for that and if you have a pulsation in the brakes at high speeds and also the steering wheel shakes a little while they pulsate then I would definately have the front rotors replaced.