the tank is supose to vent, when ever I put my lid over the filler, when closed, then put my helmet back on, it really smelled strong of gas. In my opinion, it's nothing to worry about, unless you are getting liquid where it shouldn't be. My 02 gixxer 750 did it amd y 02 gixxer 1000 does it. Mainly just make sure that the seals are in good shape with no visable damage to them.