Apple just released a new firmware update for mid-2012 MacBook Air owners. The release notes say that Apple recently discovered that a small percentage of flash storage drives in these models may have an issue that could cause data loss.
The update, available here, tests your drive and should, if there’s a problem, install new firmware to prevent the issue from happening to you.
If your drive can’t be updated, Apple will replace it free of charge. That’s big news.