Lincoln and Ann Rutledge

[LincolnMan]

I am listening to the audio book Redeemer President by Allen C. Guelzo in my car. Guelzo relates that Lincoln and Isaac Cogdale had a conversation in which Lincoln's New Salem days are talked about. Guelzo says that Cogdale asked Lincoln if he had proposed to Ann Rutledge. He says Lincoln answered in the affirmative. Then Lincoln is alleged to have said that he always loved the name of Rutledge. Since this is an audio book I'm obviously not able to discover the source material for this conversation. I'm assuming it comes from Herndon?