Jon looked at her. "I know. It was an accident. I just wanted to warn you. Keep an eye out. Everything has been boring since last night, so I figured it might happen at school. Since it wouldn't be interesting if I didn't know about it...it's going to be obvious."
Obvious is relative. Obviously, eventually Jon would notice, but that doesn't mean he would notice immediately. Things could build up for hours, days, maybe even months before he did, as he didn't specify a time frame.
It started with...personnel.
