Unfortunately

"I wish that my mother would get one wish, that I could reverse if necessary." Unfortunately, he didn't think of telling his mother she got a wish. People made idle wishes all the time, ie "I wish she'd go to hell", or "I wish I'd never had children," without thinking. Unfortunately for Jon...that was the sort of wish she'd made. Even more unfortunately, people who didn't hear the wish thought it was normal, so he'd never know what she wished for.