Henry James gets the order of chapters wrong

It turns out that for over fifty years after publication of Henry James The Ambassadors, the order of chapters 28 and 29 was the wrong way round. This error was not noticed even by James himself. The error was spotted by Robert Young (as noted in the TLS). 

Does it matter? It might not be surprising that the author did not check his own work for one of the many printings of his books. But how could a widely studied novel not have such an oversight detected? Perhaps it suggests something about the way we read James, or perhaps more specifically the way we approach James' late works. After all, James is "The Master", and masters don't make mistakes.