From what I remember, the bolt/ washer actually seat against the end of the output shaft, and there is a small tolerance for the sprocket itself to wiggle, depending on how tight the splines mate up. I wouldn't recommend loosening the bolt up and operating it, but instead checking the alignment and wear on the chain and sprockets. 17k miles is a pretty decent amount on the stock chain, and it might be due for a replacement or a good cleaning/inspection/lube.
30,000 mile 919 survivor. No plans of stopping the abuse any time soon.