What is the defined thread specification? The Cadmium thickness might not matter.
Also, holes that small may not get fully plated to the full material thickness unless handled specifically to do so using wetting agents and agitation etc during plating.
Finally I would be very surprised at being able to tap consistently to a 0.0006" tolerance even with a specially ground over-size tap.
Other's may disagree, but I would say, "don't worry about it." Submit samples to the customer QC department and see where it all falls.