Perhaps it was not a sense of dutiful obedience, but rather a certain budding pride in the bosom of Keekie Joe, which caused him to make the remark which surprised them.
He would let them know that he too had a parent, though no one had thought to speak of his parents.

If he could not have clothes like them at least he could have obligations like them.

Perhaps the true spirit of obedience was not in him.

But the point is that the poor little wretch had discovered a certain pride within himself and wished to boast of a restraint which a week previously he would have ignored.
He too had someone who was interested in his goings and comings.

So he said, "Me mudder sez I dasn' go swimmin' widout she leaves me." It was strange how Keekie Joe, who had disregarded his poor mother's wishes on so many occasions, should present her now to his new friends.
He did not have any of the things which they had, bicycles, tents, cooking sets, radio sets; but one thing he had as well as they, a mother.