Dragon Saver Gasket Kit Question.......

I installed the Dragon Saver kit on my 2010 rmk yesterday and everything went well except......I have one odd-ball o-ring leftover from the gasket kit and have no idea where it goes? Can anyone help?? It's about the size of a quarter and there was only one in the kit. I thought maybe it went to the electrical sensor underneath the under-side of the head, but that just doesn't look right. Any advice would be greatly appreciated.

It's slightly smaller than the one's that came off by the spark plugs. I replaced both of those. It's smaller, but about the same thickness... about 1" in diameter. I talked to a mechanic about it and he asked the same thing. We pretty much came to the conclusion that it was mistakenly placed in the bag with all the other seals and gaskets. Nothing leaks and it seems to run fine??? So I guess I'm just gonna go with it until I hear something from someone else or something breaks??