I don't have a coupe, so I will make suggestions that are very general.

1. Very carefully inspect the main rubber gasket. Either for a flattened area or actual damage. A cut or puncture.
2. There are drain ducts under the wing. Make sure they are clean. I believe that they start in the oval "cups" where the hinges are anchored. The exit of these are the round rubber holes under the lip by the release catch. Compressed aire to blow them out (careful!) might work well.
3. I hope not, but maybe (worst-case scenario) a leak around the glass. I really doubt this would be it-I think you would be the first.

Happy hunting, and let us know what, if anything, you find?