All,
I'm copying this from my post in the Yahoo FEH group. At least one other owner has described this very same noise. I'm wondering if it is some sort of early sign of an issue. For the record, my FEH is an AWD with a build date of 11/04, I have only 8000mi on it.

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While I was out driving today, my FEH started making a very strange
noise. I will try to describe. I was on the highway, crusing about
60mph...I was towing a trailer(see separate post) but had the cruise
on and the engine wasn't straining at all. Nearly flat...slight hills.
Anyway, all of a sudden, a rattle started from the center
console...sounded like it was behind the AC and radio controls...
sounded like it was inside the cabin (not engine). Stopped at a gas
station. As I slowed down, noise got quieter and quieter. When I
stopped...noise stopped. Opened hood with ICE running...could not
hear sound.
Left gas station...when I got at about 30mph noise started again.
Did not vary with RPMs....does not vary directly with road speed(i.e.
not like a tire noise), but will slowly gets quieter as you slow down-
-but not porportional to speed. AC Fan ON/OFF does not change noise.
The noise almost sounds like someone threw some small rocks into
a fan...almost a non-symetrical rattle...coming from behind the front
console. Almost 100% sure it was inside the cabin. Sounded like AC
Fan...but continued even after I turned the fan off. I was driving at
60mph....and just as mysteriously as noise started, it got quieter
and quieter and then just stopped. Not a peep of noise for the next
45min of driving. Weird.
Anyone have any ideas? Sounded like rocks thrown into a fan or an
aluminum can rattling from behind the dash.

Nate