SageSam

So I just had a local glass shop swap out my solid rear window to a slider (bought the slider online). While they did an okay job, the headliner is a little loose where it connects with the top of the window (e.g. a little sag).

Is the best way to fix this just applying some 3M tape? I felt around and could feel any clips, but I just wanted to make sure I wasn't missing anything. Thanks