I noticed the same noise awhile back and yesterday the deck lid ground its way into the rear window, resulting ground glass and a large crack. Scheduled for service on Monday. Looks like a design flaw, as even slight misalignment in the trunk hinge puts the window at risk.
I have a slightly different creaking trunk issue: the clamshell makes a creaking sound on the lefthand side as it opens up, as if the rubber gasket is catching on something.