Panama Canal Zone was U.S. Territory at the time...........
It was never U.S. owned land.
On January 22, 1903, the Hay-Herran Treaty was signed by United States Secretary of State John M. Hay and Dr. Tomás Herrán of Colombia. It would have granted the United States a renewable lease in perpetuity from Colombia on the land proposed for the canal. This is often misinterpreted as the “99-year lease” due to misleading wording included in article 22 of the agreement that refers to property within the land but does not pertain to the control of the canal and the right for the United States to renew the lease indefinitely. It was ratified by the United States Senate on March 14, 1903, but the Senate of Colombia did not ratify the treaty. Philippe Bunau-Varilla, chief engineer of the French canal company, told Roosevelt and Hay of a possible revolt and hoped that the U.S. would support it with troops and money. President of the United States Theodore Roosevelt changed tactics, promising support for Panama’s intermittent separatist movement. On November 2, 1903, U.S. warships blocked sealanes for Colombian troops from coming to put down the revolt, while dense jungles blocked land routes. Panama achieved independence on November 3, 1903 when the United States sent naval forces to encourage Colombia’s surrender of the region. The United States quickly recognized them. Also, on November 6, 1903, Phillipe Bunau-Varilla, Panama’s ambassador to the United States, signed the Hay-Bunau Varilla Treaty, granting rights to the United States to build and indefinitely administer the Panama Canal. Although Bunau-Varilla was serving as Panama’s ambassador, he was a French citizen and was not authorized to sign treaties on behalf of Panama without Panamanian review. This treaty would later become a contentious diplomatic issue between Panama and the U.S..
The United States, under President Theodore Roosevelt, bought out the French equipment and excavations for US$40 million and began work on May 4, 1904. The United States paid Colombia $25,000,000 in 1921, seven years after completion of the canal, for redress of President Roosevelt’s role in the creation of Panama, and Colombia recognized Panama under the terms of the Thomson-Urrutia Treaty.—From Wikipedia
By any reasonable standard there was no problem with McCain's eligibility, but the NY Times tried to insinuate that there was a possible problem in the spring of 2008 as I recall. Perhaps just a pre-emptive strike to deter people making Obama's status an issue (although that was before it was clear that Obama would be the nominee).