The memos were leaked to the AP and to TPM, and who knows who else, very shortly after the FBI/DOJ produced them to Congress pursuant to the Repub’s demands.
If you didn’t see All In tonight, watch the replay later. Chris asked Chuck Rosenthal about the disclosure to Congress, and Rosenthal said it was a big mistake, set a bad precedent, and while he is “not a betting man,” he thinks the memos will be leaked now that Congress had them. Not one minute later, Chris says, “You’re not a betting man, but I’m told in my ear that the AP has copies of the memos.”
Oh and, to his credit, Comey seems entirely unconcerned that the contents of the memos might contradict him and his book in any way.