Ashe has already told Bogert that Herbie is very advanced at mathematics, but he remains ignorant due to the fact that he is hearing what he wants to hear. Herbie, meanwhile, is trying to preserve Bogert’s ego in not revealing the actual solution in the error in Herbie’s manufacturing process, and make him feel better by telling him about Lanning. Thus, Herbie’s advancement, and the fact that humans cannot anticipate this advancement, is what causes the confusion.