2019 limited with 57k miles and finally saw the dreaded water stain on my headliner. I thought it was from the 3rd brake light since I had just swapped out the halogen for led bulbs. Pulled my 3rd brake light off and no sign of water. Also checked the the shark fin and no signs of leaking. Did check the seals on the rear window and saw some low points that fall beneath the window contact. My guess is, once the plastic cracks on the inside (which I just saw after seeing the water stain) the interior plastic will let water through from the low points of the sealant. Cleaning the water stain and sealing the top portion on the rear window. Will provide update, if anyone is interested. BTW, it's been pouring here so I believe my checks with the Shark fin and 3rd brake light are legitimate...