Hi,
it seems no one bring out this again. I discovered my GRD3 have the same problem. I called up Ricoh and manage to persuade one of the support staff to do a test for me. It proven to be a problem and worsen then i thought (he manage to reproduce it consistantly and the result is more obvious than my test).
He advice me to sent in my unit for calibration. If any interest in this topic, kindly let me know so i will continue to update.
Note: he also advice new buyer to test first, because if same problem found can immediately swap for a new set. but if only discover after one month, then can only repair