It's odd, I don't get too much water back there so I can't tell if it's from a leak, or from when I open the trunk lid. I'm pretty sure it's not the tail light gaskets. THe seal visibly looks ok. A few cracks here and there, but no chunks missing (the whole thing is in tact) and no water by the rear deck behind the seats. So, I don't really know what it is. Water doesn't exactly pool in the trunk.

Alex