Please, you really need to investigate a talking point before repeating it. Its easy to spend a few minutes researching something before accepting it as the truth.
The Panama Canal Zone was created on November 18, 1903 with the signing of the Hay-Bunau Varilla Treaty. From 1903 to 1979 the territory was controlled by the United States of America, which had built and financed the canal's construction.
Since McCain was born August 29, 1936, he was born into what was legally considered a US territory.
A Senate bipartisan legal review agreed that McCain is a natural-born citizen of the United States, a constitutional requirement to become president. Here also is reporting of a federal law suit which ruled on the issue.
http://www.wtopnews.com/?sid=1354301&nid=213