RJ;

...sound's indeed like a high likelyhood of a leaky windshield seal...they just don't seal well against imperfect surfaces after they get a little old and the rubber looses its compliance...hose test should verify (remove inner black trim to allow you to see just where its coming in, although it will travel, obiously to low spot which is, outside corners...you can even locally fold the inside lip of the seal up and have a look at the gap - probably the grand canyon - underneath)....sealing goop around the WHOLE seal, applied from the INSIDE (after letting everything dry well!) is the only remedy...

Cheers