The infraction of the rules by Jimmy Johnson's crew was fixed by simply turning a bolt. The infraction could've been a result of a bolt left loose, allowing the adjustment tube for the panhard bar to be pushed up into the rear window when the bar was adjusted. The problem was quickly fixed and fixed so it wouldn't happen again.
BTW, it hasn't been determined if any other penalties will be handed out.
NASCAR has multiple tests to determine the legality of a car before, and after an official event. Almost no one passes the first time. But, if you're found to be in violation AFTER an event, you are penalized. The crew chief is responsible for the car, his crew, everything; if something is wrong, he gets the blame...that's part of the job.