Extra o-ring with new bike?

[the_undecider_imp]

I have a customer who just bought our last new 2014 Standard. He is asking about a rubber o-ring that was in the new bike packet (with the owner's manual and other stuff) that is around 4-5 inches in diameter. He said it looks like one that you might find behind an engine case with a groove cut in it for the o-ring to sit inside (I am thinking like how some bikes have an oil filter that goes inside the engine). Anyway, was wondering if anybody else had this with their new bike. Thanks.