I believe it only applies to the supplemental Applecare, and not the initial one year warranty. The base warranty pdf never mentions accessories, while the Applecare pdf does. The key part seems to be this:
Originally Posted By: Apple
An AirPort Extreme Card, an AirPort Express or AirPort Extreme Base Station, Time Capsule, an Apple-branded DVI to ADC display adapter, Apple RAM modules and MacBook Air SuperDrive are also covered under APP if used with the compatible Covered Equipment and originally purchased by you up to two years before your Mac purchase or during the term of your APP.