Hello! I have a 24' AGP. I live in Michigan. I closed my pool about 3 1/2 weeks ago. Pool was perfectly chemical balanced and the water temp was 40 degrees at closing. The weather here has been up and down since I closed...mostly in the low to mid-50s. Since closing, I've noticed that the water level beneath the cover has already dropped about 4" (I'm able to look through the skimmer opening and see the water level's shadow on the plastic Aquador skimmer cover). Is this normal or do I have an underground leak in my pool liner? Thank you!