Neither side is flush on the 4/4S. By making only one side flush on the 5 it's easier to tell which side you grabbed as you pull it out of your pocket/purse/bag so you know to flip it the correct orientation before you ready the device in front of your chest/face.
Every Android phone I've owned is similar in this respect (as are the 3GS and below) but my 4S not so much. This move is for the best.
Every Android phone I've owned is similar in this respect (as are the 3GS and below) but my 4S not so much. This move is for the best.