Oh, no. You didn´t just tell her on what book the Tennis Balls is based, did you? Hush!
It´s one of those things that makes the book so marvellous - that you go around with the feeling... "Wait, something´s not right here." and suddenly you discover it and all the anagrams... be assured it´s all in there in the very first chapters. I´m convinced he knew perfectly well what he was doing ;-)