Probably a stupid newbie question...but i have twin 08 Yamaha 350's on my 360 Express and have noticed a mild gas smell from the outboards and a small sheen in the water after running the boat for a while. Both the smell and film dissipate after a while, and only occurs after running. There is no gas smell onboard. The engines have been running flawlessly. I have only had the boat for a few months so Im not sure if this is a new occurrence. Is this something that I should be concerned about?