I am not sure what is lens creep. But when I forget to unlock the Zoom Lock, when taking pictures, there would be a dark ring at the bottom of the pictures and when I unlock the Zoom Lock, the pictures are fine. Not use to the function yet. Was busy with my MBA exams, hence have not take any pictures since the initial 1st week of owning it.
Some pictures taken using D40X + Sigma OS HSM 18-200m at 200mm a few weeks ago. All the pictures look fine to me.