Define "retaliation". If you file a 9.5 grievance and the sup observes you to see why you're over 9.5 and notices that you're not wearing your seat belt, you can be disciplined for the seat belt. That's not retaliation. I'm sure there are other employees that have been disciplined for that issue in the past.
You would have to document specifically that this violation occurs, and the sup let's it slide, until the sup catches you doing it, only after a grievance. Good luck. Moreover, if the sup in question initiates a lot of discipline, then they're just sups doing their jobs, and the fact that you came up was a coincidence.
Of course, you can just yell "retaliation" anytime you want.