This is what amazon says it's fulfilled by amazon means:
Fulfillment by Amazon (FBA) is a service we offer sellers that lets them store their products in Amazon's fulfillment centers, and we directly pack, ship, and provide customer service for these products.
So it has nothing to do with additional warranty. If you buy from amazon you automatically have amazon's protection for anything bought from amazon.
From Amazon's website.
We want you to buy with confidence anytime you make a purchase on the Amazon.com website or use Amazon Payments; that's why we guarantee purchases from third-party sellers when payment is made via the Amazon.com website or when you use Amazon Payments for qualified purchases on third-party websites. The condition of the item you buy and its timely delivery are guaranteed under the Amazon A-to-z Guarantee.
This applies to purchases made on the Amazon.com website. For purchases made on third-party websites using Amazon Payments, go to
Amazon A-to-z Guarantee on the Amazon Payments Help page.
Customers who pay for purchases from an Amazon seller via the Amazon.com website are eligible to receive up to $2,500 of the purchase price, including shipping charges.