Hello, Had a new 24' x 52" professionally installed about 3 weeks ago. Needed to bring back side of pool up 11 inches or so to be level. 3/4 stone and stondust mix for base. Second was all stonedust then the sand, all was leveled with a lazer . After some heavy rain on and off for a week or so I noticed the water looked lower on 1 side, found about 1/2 inch difference. After it was installed it was pretty much even all around. Is this normal for some settling or should I call back the installer. Any thoughts would be great. Thanks for your time..