updated 03:22 pm EDT, Thu May 16, 2013
Update mandatory, Apple says
Apple has posted a new support download for mid-2012 MacBook Airs, MacBook Air Flash Storage Firmware Update 1.0. Unusually, Apple states that the patch is mandatory; it fixes a problem with the Air's firmware that can, potentially, prevent a computer from recovering from a crash. The file is a 1.69MB download, and requires either OS X 10.7.5 or 10.8.3.