Ours was so perfectly level (I made my DH crazy with the transit several times a day during install) when we prepped and installed in our usually wet yard and then we had the "big drought" this summer (biggest in the northern plains since 89) and even a lot of the normal subsoil moisture dried up. So, long story short, our "plump" ground shrunk and shifted slightly back there and I do notice a slight difference of maybe 1-1.5" or so - not side to side but from one end to the other. I'm hoping that we do not have an unusually wet fall or spring.....