It's seems to be a matter of refinement and genetics.
Definitely, the more bags you have the better chance you'll have at getting FMCD. The further refinement attained by more bags means less contaminants in your 73µ and 90µ. I have been told that people can get FMCD in other screens as well.
For reasons that I am unfamiliar with, certain strains have a much higher tendency to produce FMCD than other strains. Perhaps it's the ratio of capitate-stalked trichomes VS. capitate-sessile and bulbous trichomes, but that is mere speculation. If anyone else can clarify, please do.
Subtle is the Lord, Malicious He is not.