Pad mileage is like fuel mileage, it will vary WIDELY from one driver to the next.
One thing I would mention though is that disk brakes unlike drum brakes will wear out pads in NO TIME if you even BARELY touch the brake pedal while driving. The pads retract only a hair from the rotors when removing your foot from the pedal. Barely touching the pedal will cause pad to rotor contact and they will be gone almost immediately.
Another thing to consider might be the condition of the bores and seals. If they were really dirty and gritty, it could be that the pads do not retract thus causing premature wear. this would most likely happen with only one pad. It only takes one pad to wear down and make contact with the wear sensor to illuminate the lamp.
If you pull both wheels and inspect all four pads it will tell you if you have a bad piston/bore or if maybe your toe rests sometimes on the brake pedal. IF the toe on the brake pedal is the problem, most likely you brake with your left foot. You can correct this habit by using your right foot only for braking and throttling both.