Canon, Inc. has issued a similar Canon EOS 5D Mark III service notice (Google translation).
Canon, Inc. adds that a "dark environment" is likely to be:
1. If you have installed the body cap
2. If you attach the lens cap
I've been asked if I am going to send my 5D III in for service. My answer was probably, but mostly for resale purposes. But I will not likely send it in anytime soon.