If you've downloaded ios 7 to your phone listen up, there's another bug.
If you have your iPhone in Airplane Mode programs needed to retrieve a lost or stolen phone such as Find My iPhone is rendered useless. And it could give thieves extra time to spoof your fingerprint and hack your phone. They could even use the "forgotten password" part to have a new password made.
There is a fix though. Go into your "Settings", then "Control Center" and switch off the "Access On Lock Screen."