So, with the release of the new intel Haswell-based MacBook Air in mid-2013, Apple made some slight tweak to the MagSafe 2. They made it stronger, so that it didn't detach that easily.
I have a brand new mid-2013 MacBook Air 13" and I found, to my dismay, that the MagSafe 2 is just too strong. The magnet is so strong that I can lift a MacBook Air with it:
The product is not working as designed nor as advertised! I want my money back!
2013 MagSafe 2 is too strong! from Ringgit on Vimeo.