I hope this isn't related to the recent Mouse Hotel posts. The windows of my 4 month old Prius were fogging up so I turned on the front defrost and to my surprise about 5 bits of gray foam shot out of the dash duct. I increased the fan speed to maximum and about 15 more bits blew out. My first thought was mice chewing/nesting in the ducts. I sniffed a couple of pieces and didn't notice any mousy odor. I would say this is ominous. Guess I'll have to call the dealer.