I have a 2010 with a leaking rear window as well. I took it in and had the seal replaced on the rear window BUT noticed a couple of drops this morning on the cargo cover so I'll be looking into that.
*EDIT* Ok we had some rain here yesterday...last night and again a bit this morning and I checked 3 different times and NO water inside the rear hatch area.
I just had the leak repaired Wednesday so MAYBE those couple of drops that I saw were leftover from the dealership testing the area and not new wetness.
I will report back later if I notice anymore water but it may have been repaired properly.