Buzzing rattle in door pillar

[TwoBearWisconsin]

I have developed an annoying buzzing/rattling sound in my Yaris 5 door. It sounds like it is coming from the door pillar or the area where the seat belt comes out. Kind of like a metal wire is rubbing on something. It's not constant - I hear it some days and not others. When it's buzzing I even hear it when I close the driver's side door after getting out of the car.

Any one have any ideas what could be causing this, and how to get rid of it?

Thanks!