I received my new 11 inch 2013 Macbook air a few days ago and when i charged it to 100% it only said 5 hours and 22 minutes of battery, isnt it suppose to have about 9 hours of battery? I have the screen on max brightness, keyboard backlight off and bluetooth off. And the OS is 10.8.4, is there a way to fix this or did i just get a defective unit?