Sometimes tiny gravel or dirt get's stuck between the front windshield cowl and the bottom of windshield and causes these rattles that seem like it's coming from the dash. Pressure wash the area out and see if it helps.

Granted, even without dirt there, I still get random rattles from the dash when it's colder out. Just turn up the radio

Personally, I wouldn't bother taking it in to the dealer, I mean even if they actually do give a damn and try to help you, would you really trust they will meticulously take apart the entire dash, and put it back together EXACTLY how it was from the factory? You might end up creating new squeaks and rattles in the process of getting rid of this one, lol.