I drive a wonderful 2007 Hyundai Sonata....love the car in all ways. but, it ain't perfect.
Had to go see the dealer cuz the power lock on the drivers door was acting kinda 'wiggy'.
Dealer replaced the switch....problem solved.
It happens....complicated machines are ...complicated.
It's a constant source of amazement to me that all the gazillions of cars, trucks, bikes, boats etc etc etc built every year world wide ,roll of there assembly lines completely fault proof...IMHO personal transportation devises ; for better or worse, are a miracle of engineering and testament to mans creativity and ingenuity. Just as surely as is Puccini's "Tosca", Da Vinci's 'Mona Lisa, or Aaron Copland's "Appalachian Spring".
( think of it this way...for every single nut, bolt, washer, fuel tank filler cap seal, table spoon, 'do-hickey' there's a drawing or 'spec' sitting in a drawer or computer file somewhere that someone had to make so the simplest of things can be made! It boggles the mind that any of it works at all).
So, It may just be a faulty seal. I'd say go see the dealer. cuz sometimes 'chit' just happens.
(something that we all hate to acknowledge on something we are so fond of).
And stop overfilling..for petes sakes. LOL wink wink wink.
OK...I'll shut up know.