i thought the metal popping and clicking only occur to big truck or older vehicles. Mine is very compact and has around 300 miles to it. My friend also has a civic (2003) and there is not a single sound you can hear after he turns his engine off.

 

i would take it to the dealer and have one of the better techs look at it, but chances are, its just the exhaust system cooling. but hey, thats why you buy a new car with a warranty, right? but as its new, a lot of times, a newer car will have strange smells and sounds after you drive it, as all the parts are still being broken in. they usually fade as time goes by. but go get it checked out, we could be wrong here, its hard to tell without actually being there.