Rattling in front passenger dash

[sr7628]

I've had my Yaris for about a month now, and since maybe a week after purchase I've been hearing a rattling/clicking sound coming from the front passenger side of the dash. Sometimes it sounds like it's coming from there, other times it sounds like it's coming from behind the speedometer console. The thing that kills me is that I don't hear it consistently...when I do hear it drives me nuts, but some days I don't hear it at all. I think I've come to the conclusion that it only makes the sound when it's cold outside, and since it's spring in North Carolina, that varies on a daily basis. I'm also wondering since it's caused by the weather, if it has anything to do with the windshield glass, as that expands in heat, right? That could make for a tighter seal in warmer weather and a looser one when it's cold?

Has anyone experienced this problem who can give me some tips? I took it into the dealership and they placed the blame on a broken cd case in my glove box, but that's obviously NOT the issue!