Age Swap Stone: The Closest Person

Standing in the hallway as he was, Jon was unaware of the changes starting to occur. The wish was granted, and the side effect started to assert itself. Jon noticed it as an odd blur effect across his vision very different from his previous wishes. And when it cleared, instead of being dressed and heading downstairs, he was back in the bathroom taking a shower He nearly slipped in surprise. How had his wish caused this?