Did Dickens omit something he promised to revisit or did I simply miss it?

I just finished Dickens' "Barnaby Rudge" (audiobook).

Because I was listening rather than reading, I can't go back to the specific page about which I have a question. In any event, at one point after Barnaby and his mother are discovered, they run into a country gentleman who wants to buy Grip, but Barnaby refuses to sell him. After this distasteful episode, the narrator says this incident will be important later in the story, but as best I can tell, it never comes up again!

Did I miss it someplace?