Although not as widespread as the issues Apple recently fixed with the “MacBook Air (Mid 2013) Software Update 1.0”, a growing number of people are reporting problems with late model 2013 MacBook Airs (Mid-2013 Haswell-based), where the display will randomly go black.
When this happens, the display may just intermittently blink to black for a second, or the MacBook Air may actually go to sleep requiring to be woken up. This seems to happen more frequently when running off battery power. Both 11-inch and 13-inch 2013 MacBook Air models have been reported to have this bug.
Currently Apple is trying to figure out the root case of this, and is swapping out logic boards in some cases. Resetting the SMC can prevent the problem for a while, but this apparently is not a permanent fix. It is likely Apple will be releasing a SMC firmware update in the future to address it.