Funny old thing.. I just started hearing a very annoying rattle in my truck that seems to be coming from the same place. It sounds like something is loose inside the trim... rattles only when going over very small bumps, not big bumps. It's bugging the piss out of me because it constantly rattles when driving on the freeway.
However, one thing I have learned in years of owning rattling cars is that rattles often come from nowhere near where you think they do. The inside of a car is a big echo chamber. Although mine sounds like it's coming from the driver side door pillar I'm planning to check the entire vehicle this weekend to try and find it. Could be the sunroof, could be the headliner, could be from the trunk or either door. I've no idea. I do know it's not the infamous rear seat latch rattle (I fixed that) and I'm pretty sure it's not the sunroof (that has a very unique rattle). I hope I find it.
I'll keep you informed.