Ah, what a pain!
I because of some issues, I once sent in my GRD III. Before, focusing was working fine, but after they exchanged the lens assembly, I sometimes get focusing errors.
The macro focusing issues are one thing (which my camera also suffers from), the other is that the camera seems to front focus (that is, focusing on things nearer to the camera, right?) occasionally.
I focused on the edge of the seat of a chair, holding the camera about 1 meter from it in a 45° angle. When I reviewed the photo, focus was more on the upper part of the back of the chair. The edge should have provided enough contrast for reliable AF...
After checking the amount of back focus in Macro AF, I noticed that it back focuses to nearly same amount it front focuses in Spot AF, that is roughly 30 cm.
The front focusing is somewhat harder to reproduce. I only (or mostly?) experienced this problem in very bright light or light reflecting off surfaces like a white wall or that wooden chair.
But then, under the right conditions, this problem remains quite reproducible and consistent.
Generally, focusing accuracy seemed to have dropped quite a bit after I sent the camera in.
I guess I have to call Ricoh support :/