I got a call the other day from a homeowner. The lawn was soded 1-2 years ago. The sod seems to have lifted from the soil. Its rooted in ok, because you can't lift it up. When you walk across it and stomp on it, it will push back down, about 1"-2" What would cause this? Did the frost heave it? Did the soil settle? The lawn has an irrigation system, is he over watering? Anyways, I was thinking rolling the lawn and hoping for the best. Any opinions please. Thanks!