I'm sorry I'm coming into this so late but I think I know how to fix it. I just did it myself. You know the accordion-style close outs on both sides of the glass? Put the sunroof in vent position and then pull the close-outs off their top clips. Youll see a torx screw in each corner. Typically, this means the front two need to be loosened, push up on the glass and tighten them. I did it last week and my sunroof hasn't sagged once.

 

Just like in post #18, from 2010?