After heavy rainfall or a long spell of rain I have noticed that when I open the boot of my A4 cabriolet about half way a stream of water pours out of the grommit that holds the carpet in place!!???? There is no water in the boot and it just seems to collect within the double skin boot lid, does anyone else have this problem? and what is the best way to stop it? There is no visible signs of any damage to the boot lid. Any suggestions ?