Just noticed this thread (no pun intended
). I had trouble with the seat stitching on my 1999 Caprice. Same car maker -Holden, same seats.
I found the stitching on the passenger side bolster started to come apart. When I had the cover taken off, whoever first assembled the seat did not put the foam rub material over the side air bag so the airbag cover was rubbing on the inside of the leather. Didn't cost much to fix it but that was about 15 years back. Still got the car today.