Funnily enough... When I bought my GTI, the first time I filled it up I noticed behind the fuel door was completely filthy. I cleaned it out a bit and got a new fuel cap. Was just cleaning it the other day and gave the inside of the door a bit of water thinking I don't want it to get dirty again. I noticed, as I have done before, the the way just sits there and thought what a crap design. Then all of a sudden it drains out! The pipe must have finally unblocked itself. I didn't even know it was there.