Now playing: Watch this: Unboxing Apple's iPhone 5S

US consumers hunting for the iPhone 5S may find it in even shorter supply these days.

Stock of the new phone has plummeted in the US from 27 percent of all iPhone models available to just 6 percent in the past week, says Piper Jaffray analyst Gene Munster. Based on checks of 60 Apple stores in the US, Munster also found that the percentage of stores with at least one model of the 5S fell to 40 percent over the past week from 90 percent two weeks ago.

But the 5S may intentionally be playing hard to get, suggests the analyst.

Apple could be limiting the supply in the US in preparation for the phone's impending launch in more countries around the world. Both the 5S and 5C are due to land in more than 25 new markets come October 25, followed by another 16 on November 1.

Apple's online store in the US and other countries still shows an estimated ship date of sometime in October for the 5S.