I got this noise this morning when I started my truck. It came and went with the RPM of engine. It seamed to come from the underside of the drivers side dash. I thought it was because of the cold temp outside. I was about -17c. I have 10800 KLM's or 6700 miles on my truck. If I get it again I'll take it back to my dealer and have them look at it.
Autonut