Something vibrating in passenger side dash area

[BlueHUMMERH2]

I've had that problem. Never really figured out what it was. When it happens I either tap the dash near the daylight sensor or push on the handrail above the glove box. These actions usually make the problem go away for a while.

Even when I installed the SIR GM1 behind the glovebox, I came up with nothing that could be rattling that was obvious. I thought maybe the daylight sensor, but it appeared to be secure.