But this isn't just about the FBI. It's about all of law enforcement. Sure, the FBI may be practiced enough to hide the facts of discovery, but will every law enforcement agency in the US be as adept. If Apple is lying, or law enforcement finds a way to circumvent the encryption, it will most likely leak at some point, an leaks are becoming more and more common, especially with highly visible targets like Apple and Google (both blackhats and white hats are itching to show up the tech giants).