yeah.. um.. don't even drive to your dealer.. don't drive the car at all if you've got a fuel leak. call a tow truck company who knows what they're doing and have it towed to the dealer
that doesnt sound like overfilling ... i'm not sure about on your A4 but both my jetta and allroad have a little drain right underneith the hole where the nozle goes. if you overfill, itll trickle out on the right side of the car.