That's making me wonder just how much they took out the drums. The max machining on those is .060" over the nominal. At that spec, there should still be decent contact (not the best, though). If they went to throwaway spec (.090" over nominal), the drums need to be replaced. They should have given you the after machining measurment. I always do on any carry in drums or rotors.
BTW, I beleive Carquest sources their brake friction from Wagner.
