The seals are OK, but the design of the window requires that the track inside the door and the gusset hold the glass tightly against the seal. But people open and close the door by pushing on the upper corner of the frameless glass, which exerts a lot of leverage on the track and gusset. Over time, they no longer hold the glass tight against the seal.
Remedies are to pinch the gusset and stuff plastic tubing into the seal. Also to remove the interior gusset cover and close up a hole to the mirror.
I have avoided touching the glass when opening and closing the doors, and my 2008 is quiet as new.