Our 24' above ground pool has been covered for the winter. We are planning on opening this weekend. Over the past week or so we have noticed that the water level has drastically dropped (we drained in just below skimmer for the winter and now it is about 1' below skimmer and most of that recently). It looks like our pillow has deflated, but I don't think it would make that much of a difference. Any ideas what could cause this or if I should be looking for anything once it is uncovered? Is it possible something could have happened to the liner even though it is covered?