First thing to check is if the rotor is always spinning 'off' by that 1-2mm you speak of. Remove the caliper from the frame and then spin the wheel (Just to make sure the caliper isn't inflicting any forces that would cause the rotor to bend further unpredictably.) If the rotor isn't wobbling back and forth, that isn't the cause of the problem although it might do you some good to reposition the caliper in regards to the rotor.

If the rotor IS wobbling, well you probably should replace it or get it put back into shape (Likely easier just to replace it, at least given my expereince working on them. If it's a brand new rotor I can usually get it pretty decent into shape using the proper Park tool, otherwise things get more interesting.)

Even if it doesn't solve your problem, you'll have the comfort of knowing that your braking will be better as a result.