I have a 2013 and don't recognize it, but not saying it didn't come from your bike.
Is that one of the caps that covers the screws on the luggage rack?
i used to work on an assembly line at caterpillar, some times a cap or other item would fall from a torque tool (or impact tool) into the tractor. we never looked for it, we just called the small-tools mechanic to replace it.
What? Coffee ISN'T free?
Rode-map
This reminds me of a friend I worked with in an I.T. group years ago. He was a brilliant software and network engineer, but not very mechanically inclined. One morning he pulled his Camry out of the garage and noticed a part on the floor. That was concerning, so he stopped by the Toyota dealer to ask a service writer what the part might be. 'Looks like a roller off of your garage door' was the reply. He was a little embarrassed, but said the service department found it entertaining.
I'll save it, certainly belongs to something. Guessing it's not to the wifes newer car, maybe some tool I used and found it's way to the floor.
2013 F6B 1800B
Don't be a thermometer, be a thermostat
Looks like a decorative endcap for tubing, to me. Wherever it goes, I don't think it being missing is gonna hurt anything.
Could it be a cap for the end of some foot pegs?