sunroof whistle

This week the sunroof on my 2013 Passat has started to whistle and for a 70 mile round trip commute it's very annoying. Any thoughts on why this started or what can be done to fix it? From the outside it looks the same as it always has.

Did you go through rain by any chance? Drain tubes will collect some water and the pressure differences tend to cause a whistle. We really like our SEL but no sunroof makes my SE a better car.

Have you tried opening it and closing it? It may have gotten out of position slightly, or perhaps something got caught in between the roof and the glass's seal.