I went and got the plot coupon “Secret Documents” from the Old Alexandrian Outpost before I first met with Atticus in Riverdale. Atticus promptly skipped the exposition explaining his relationship with Dante and went immediately into the text dealing with returning the plot coupon. I only learned the gist of the exposition by reading the strategy guide.
I ran into a similar situation at the Small Farm, when I defeated the Mutated Merman before speaking with the farmer. He paid me the “agreed upon price” despite my not talking to him before.