Mikey was very lucky, in the time he had started asking his mother questions like that, she had in her annoyed state set the rock down, and when she made the wish, she was not holding it. He was not changed like he could have been, and the thoughts of being more careful settled into his mind.
His mother looked at her watch and realized she needed to get ready, so she went upstairs, leaving the rock unattended, right in front of Mikey's eyes