Loosen up the three screws on the striker...just loose enough so the striker will move by hand. Then gently close the hatch with the key turned so it won't lock. Push down on the hatch so as to compress the hatch seal only a little.
Then gently open the hatch (with the key still turned). Then tighten the three screws on the striker. (the striker shouldn't have moved when you opened the hatch) Test the operation.
You can check the seal tightness using a dollar bill. It should be pinched all around the seal with the hatch closed/locked.
Along the lines of the hatch, mine has developed a rattle over the past couple of weeks. Still opens and closes fine, but I'm guessing that it somehow needs adjustment. Would this be in a similar manner to what was discussed above?
^^^^Check the striker itself. On my '06, the plastic covering on the striker post, was completely worn through on the back-side......and was rattling. I had to get a new striker (under warranty) to fix the noise. Lube it up good with heavy grease.
My striker appears fine, still wrapped in plastic. I've tried messing with the rubber dampers, but that doesn't seem to affect things. Its a pretty audible 'clunk' when I go over any kind of pavement imbalance. Definitely coming from the hatch. And, its the only rattle I've had on the car in over 95,000 miles....