Has anyone experienced this? My 2004 GTI started emitting a musty smell through the vent about a month ago when the a/c was off.

I took it in to the dealer -- they said the smell was not under warranty, which was kind of amazing. They flushed the water (or something) in the a/c.

It smelled linen fresh for a while afterwards. Now I can smell the musty smell again.

Does anyone know what's causing this? Has it happened to you?