Tank Breather

after looking at pics (yours and warps) i checked mine(07) and i think that the cover looks like it might seal the raised tank vent that warp pics shows and then my cap has a rubber seal that goes against the big hole and seals the tank. on your pic i do not see anything that would seal the large hole in the top of the tank and if i am wright the gas would (when expanded) just go out the exhaust tube onto the ground.

Thinking about it I may have had fuel splash out at the bowser and leave fuel in the top of the tank. As I have filled three times since and no issue