Honestly, top / bottom differential isn't usually a concern as long as R/L match up, but 3" is quite a lot... Guessing they're fairly old and flown in (stretched out), or whoever made them didn't put a good pre-stretch on them.
Easy fix in any case, as @Bunduki Vlieger said:
3 inches / 7.5 cm that's a lot! What are these lines? New? Used?
I would definitely reknot the loops and adjust the length. @John Barresi has a video tutorial on this here: https://kitelife.com/video-tutorials/