Answer:
The cause of Aibeleen's bitterness was to recognize that "seed" for saying so or that new trend or habit that perhaps she has acquired, the good thing was that in a short time she recognized it.
Explanation:
The Aibileen precisely recognized that change that took place within him, which apparently was not for the better, because as he says it was a cause of bitterness, or it could be, that the change involved left some habit or good habit that perhaps it had.
