My 06 does the same thing, but it's most annoying when I make a right turn on unlevel ground (like turning into a steep driveway). I get a creaking sound coming from the right rear of the cargo area. I assume it's coming from where the hatch meets the body - when it flexes, the hatch and body move a little. I'm going to bring it up when I take it in to the dealership for the first oil change. Hopefully they can figure it out, cause it's really annoying!
Oh yeah, when I open the hatch, it sounds like the latching mechanism is really tight and pops undone. Perhaps it needs some adjustment or wearing in cause it's new? Anyone else get the feeling that it's not as smooth as it could be?