My Dad's SRT8 did this too, in fact I posted a thread here asking about it - - His has 1200 miles on it now; couple days ago I changed the oil for him (yeah i know you don't have to do it that soon but I figure it doesn't hurt after the initial break in of a new engine...) and washed it and I didn't hear that sound even once. Of course I had to test drive it after changing the oil; got it good and warmed up....no noise. I'm gonna call it fixed for now.