I am just wondering: do camera makers ever make unannounced fixes or mini-upgrades to their products (besides firmware updates). I ask for this reason. With computer CPU's, sometimes you could buy an later version of the same CPU speed rating (say an Athlon 1700 MHz) and it would overclock higher than than a CPU bought say 6 months earlier. The production yields were better, I guess.
I know that camera makers make slight adjustments in their camera before coming out with production models. Do they ever slightly improve their cameras within the same model (not counting firmware upgrades)? So maybe there would be slightly less noise or faster focus or better buffering or whatever?