Why does Stacey act distant to Mr. Morrison?

Stacey is under the impression that Mr. Morrison is undermining his position as man of the house while his father is away working. He's somewhat jealous and believes that possibly his father doesn't trust him to look out for his family. Stacey is quick to change his mind when Mr. Morrison picks them up after the tussle at the Wallace store and tells Stacey that he won't tell Mama what happened, but that Stacey will have to man-up and tell her himself.