[MsPCGenius]

We have the same issue with our 2 yr old house. Back yard is very lumpy-bumpy, but it is not due to uneven ground. We have been able to easily determine that in several spots, the sod floats above the ground -- in other words, the roots have taken hold but not strong enough to pull the sod even to the ground. We thought about renting an aerator, but don't feel it necessary as many of the mounds have actually begun to settle. As the grass greens up and becomes healthy, the roots are beginning to take hold.