Apple has just released a new EFI software update for their latest mid-2013 MacBook Air models. The firmware update is meant to address minor issues related to Boot Camp compatibility with Windows 8.
From the release notes:
MacBook Air EFI Firmware Update 2.7
This update is recommended for MacBook Air (mid 2013) models.
This update addresses an issue which may cause a black screen to appear when installing Windows 7 or Windows 8 using Boot Camp Assistant if both an external optical drive and USB thumb drive are connected to the system. This update also ensures that the system will boot by default into OS X after installation of Windows 8.
The update weighs in at a mere 4.8MB, and is available now via Software Update, or for direct download from Apple’s support site.