If you read the text, she says she uses code to send classified information through her home server over the holidays when most people aren't near a secure network. Just her breaking the law again, unfortunately doesn't directly correlate to their everyday use of code, but does show that they each have the key and capability to constantly communicate in their own code. Quite interesting.

Edit: TL;DR: the gun is still not smoking. Look for holiday emails and the code they made be using