2015 rMBP lid loose

The only thing you can do is get a spring scale and carefully attach it to the top edge of the lid with the lid slightly opened see how much pull it takes to open then do the reverse closing it. Take note of these measures then take your gear to an apple store to compare with their store samples or someone else's (same model).

If you find it doesn't take as much force you'll need to speak with Apple on getting it fixed. Without the data to support your position you won't have much to stand on. This will require a new display assembly to replace the clutch hinges.