The first-generation Apple Watch suffered from a few problems, including "ballooning batteries" that ended up displacing a few users' screens. In response, Apple quietly extended service coverage on first-gen device battery issues for an extra year. Now, they've done it again in response to another issue: According to MacRumors, first-generation Apple Watch owners can receive a free repair if the back cover of their device separates from the watch.
First-generation Apple Watch owners who encounter this problem will have a total of three years of coverage from the date of purchase. If your Apple Watch has this issue, you can schedule an appointment at the Genius Bar or an Apple Authorized Service Provider. Additionally, you can call Apple Support and mail the watch to an Apple Repair Center.
Take note, though: While Apple has circulated an internal memo on this topic, they haven't made the policy public. There are some reports that Apple Watch owners were required to pay for their repairs, despite the warranty extension. If you encounter this problem, escalating your request until you find someone who's aware of the policy should do the trick.