What's more is the app update mechanism. From a technical standpoint, Apple just has to deliver an app update via auto-update to a version of an app that has the necessary access
But conceivably apps can't update when the phone is locked?
but whenever you are using your phone, it is unlocked and not encrypted and all data could be transfered at that time (or any update could be installed)... 4G is pretty fast and it would not take very long and could be hard to notice.