Can you identify this extra Spring - license plate maybe?

[Allen42]

So, I found a spring laying behind my bike today in the garage. Pic attached, key for scale. I *assume* that maybe it's some sort of tensioner the dealer put under the wing nut on the license plate bolts, as I finally received my license plate and swapped it out the other day. I didn't notice anything fall while doing that, but that's the only thing that makes any sense to me. If that's it, the other one is probably sprung somewhere in the garage, and I'll have to look for it. But, I wanted to see if any of you recognized it to put my mind at ease.