Grass sprites "sinking" into the ground

This is pretty minor in comparison to most bugs but I figured I'd mention it in case it's a symptom of something larger. I came back to Round Hill after running around the map for some time and noticed some weird "sprouts" on the ground:

http://img27.imageshack.us/img27/623...2363444.th.jpg
http://img231.imageshack.us/img231/4...2363449.th.jpg

On a hunch I guessed that I was seeing the top of the grass sprites and that they were underground for some reason. So I relogged and saw that I was right:

http://img834.imageshack.us/img834/9...2363613.th.jpg
http://img831.imageshack.us/img831/2...2363622.th.jpg
It seems like some positional error built up as I was running around maybe. I didn't notice if other decorations or items also dropped below the terrain and I haven't done as much running around since this happened. If I see this again I'll be sure to check other objects.