Apple has released MacBook Air Flash Storage Firmware Update 1.1. The update can be downloaded by running Software Update on compatible MacBook Airs. The update is for mid-2012 MacBook Airs and will, in most cases, install the new firmware. But the update also checks the reliability of the MacBook Air's drive to save data and if it is found to be faulty, Apple will replace the drive. From the update's release notes:
This firmware update is recommended for MacBook Air (mid 2012) models.
Apple has discovered that a small percentage of flash storage drives in these MacBook Air models have an issue that may result in data loss. This update tests your drive and, in the majority of cases, installs new firmware to resolve the issue. If your drive cannot be updated, Apple will replace it, free of charge.
If your drive is found to be faulty, Apple has detailed how to claim a replacement on the MacBook Air Flash Storage Drive Replacement Program page.