When Owen Wister, the famous American novelist of the late 19th/early 20th century, was on a trip out West, somehow a report started that he had died. He was on a camping trip and didn't find out about it for some time, but all the newspapers in the East picked up the false report and published obituaries. His wife even got on a train to head west to recover his body. It took days for the mistake to be discovered and corrected, and he said he sometimes shocked people long afterwards, who exclaimed, "But I thought you were dead!" He often quoted his friend Mark Twain's famous comment.
Most newspapers have prepared obituaries in their files for noted persons of a certain age, and someone at the NYT probably jumped the gun to get theirs out first.