I wasn't aware of that either but I just checked my Amex card and here's how it read:
With Extended Warranty♦ you can shop with less worry knowing the terms of the original manufacturer's warranty can be extended up to one additional year. Applies to warranties of 5 years or less that are eligible in the U.S. Please read important exclusions and restrictions.
Thanks for pointing this out Neuro....I will definitely be using my Amex for all future purchases of gear and equipment that has a warranty.
It is a terrific feature from Amex, but as Neuro says, some other cards also offer the benefit.
I think this is a global benefit from Amex.
I always smile when I get an email from Canon asking if I want to extend the warranty for an extra year. No need!