I love my 11" Mid-2013 MBA! However, it has an annoying problem of going into power saving mode and not coming back if you touch it at the wrong time. I'll attach the bug report (15550585) I submitted to Apple. They closed the report since they said it was a duplicate of another bug report (15556091):

Summary:
On any mid-2013 MBA (11" or 13"), when system is idle long enough to dim the display/go to sleep, the screen fades to black. If the user tries to prevent sleep by tapping a key or trackpad, the system hangs with a black screen. The CAPS LOCK key toggles on/off when pressed, but no other user input seems to do anything. Closing the screen and reopening has no effect. Only a hard boot will bring system back. The happens whether on battery or plugged in. Any unsaved documents/code files are lost.

Steps to Reproduce:
1. Let system idle and wait for display to dim (based on power settings).
2. Wait a couple more seconds for screen to go black.
3. Wait a split second more for keyboard backlight to begin to fade.
4. Before keyboard backlight is completely off, press a key or swipe the trackpad (as if trying to prevent the system from sleeping, thus requiring re-entry of password)

Expected Results:
I would expect the system to wake up and let me continue with what I was doing.

Actual Results:
When touching the input as the keyboard backlight is fading, the backlight illuminates brightly, but the screen stays black. The CAPS LOCK key will toggles its light on/off. No other action will wake up the system. Only a hard boot will bring system back on.

Version:
My personal machine is a mid-2013 MBA, 11", 256GB SSD, 8GB RAM, i7 chip, currently running Mavericks, but issue first noticed out-of-box running Mountain Lion.

Notes:
I brought my MBA to an Apple Store on 11/2/2013 and demonstrated the behavior to a "genius" with my configuration running Mavericks and when booting to Apple's "known good" environment running Mountain Lion. My case number is 524999600. I first announced my findings on the following discussion thread with the username "Yoganinja": [...] Many others have been able to reproduce.

Configuration:
Any mid-2013 MacBook Air. Off-the-shelf models, brand new or refurbished. Custom models, brand new or refurbished. 11" or 13". Mountain Lion or Mavericks. Out of the box, or with additional software installed.