I recently purchased a 12X20 oval pool and had a professional company install it for me last summer 2 feet below ground. I noticed this year that I can see the imprint of bolts on 2 of the wall joints on each side of the skimmer. There are no punctures in the liner yet but I am nervous about this. I would say they come out about 1 cm. I am wondering what could have caused this. Maybe a shift in the pool as it settled? The bigger question is what happens if the liner breaks? Can some please help this new pool owner. Thanks in advance!