Does anyone have an idea what might be causing a metallic rattle in the headliner directly over my left ear? It seems to be coming from the grab handle/airbag area. I've pushed, pulled, and punched everything in that area and nothing stops it. It's not the seatbelt anchor...I already tried that.

 

This is going to sound silly, but check to see if your sun visors are clipped in or just pushed against the clip(s). I thought I had my first rattle when the driver's sun visor was pushed against the clip but not inserted. The rattle was a metallic multi-click noise that sounded like it was coming from anywhere but the visor area. After insertion of the visor rod into the clip, the rattling stopped.

 

Dude....that was totally it. I've been listening to this rattlle right above my head for ~5000 miles and that's all I had to do. Thanks a million!! I feel like a complete idiot.

 

That's how I felt-- it took two days to locate it, and I was going to call for a service appointment with Acura when I found it.
Glad your "rattle" was not a real one!