I don't think it's ever been a secret that the NSA can monitor communications of all sorts, including phone calls.
Exactly how they do that has never been clear.
This NSA phone eavesdropping argument goes way back, too.
I have no doubt that had the NSA been interested, they could have recorded CGM's cell phone calls that night.
That creates a problem, though. If you reveal info that you could only have gotten a certain way, you reveal that you can do certain things and that you are doing them.
My herding skills aren't quite what they should be... but we got there...
Good point...