Sorry to burst your bubble....
But these are Made in China now. There is a chance of getting leftover USA, but all these sets produced in the last month or so, and going forward are 100% made in China. Both the case and the nutdrivers. So YMMV for USA on this.
Currently, the only way to guarantee 100% USA nutdrivers is to buy the 7-piece Metric nutdriver set and the 7-piece SAE nutdriver set. That will give you a 14-piece USA nutdriver set (includes 2 extra pieces, smallest Metric and smallest SAE size). But I would imagine both of those 7-piece sets will go China once stock runs out and they produce future runs.
So if you want USA nutdrivers, better jump on something now.
EDIT: PS - Your best bet at finding the 12 piece zippered case still Made in USA is to buy it from your local Kmart store. Because the stock on these moves slower at Kmart.
Also, the price is cheaper from Kmart, only $15 right now for the same set. Go over to your local Kmart, pick through them, and grab a USA set.
http://www.kmart.com/craftsman-12-pc-nutdriver-set-in-zippered-case/p-010W065282428001P?prdNo=1&blockNo=1&blockType=G1&sid=KAx20050801x13xSlickdeals&aff=Y&PID=4485850&AID=10660381