I just had a new 15x30 52" above ground pool installed. After a week you could see a section along the one flat side start to bow and get out of line. I called the installer and he came back and had to realign everything. He said the bolts that hold the upright to the bottom plate broke and it allowed that upright to shift. Now after the re-installation, it seems like the walls is bowing out between the uprights that he just fixed. Is it normal for the straight side walls to bow out between the uprights? It seems to me that there could be a lot of pressure pushing on those sections once the pool is full and cause a premature failure. Any one out there have any insight?