Headliner sagging in passenger rear

[Alex Jernegan]

Hey does anybody know what might cause the headliner to sag this way? It’s in the passenger rear and it brings the weather stripping down with it. I know the sunroof sag is a thing but this might be something different. I do have the surround sound speakers. What would be the solution to this and maybe the sunroof headliner sag, I don’t want to drill into the headliner. Thanks in advance

 

[Bigskyroadglide]

It's getting wet is my guess. Probably from the third brake light