Basically, there are four stages of mold. "Plume," sometimes referred to as "Bloom" is actually a precursor to mold. It is part of the aging process, especially with certain kinds of tobacco, and is considered a "good thing" by cigar connoisseurs.
If a cigar with a lot of "bloom" on it is allowed to age at humidity levels that eventually get out of control, it actually becomes "white mold" or morphs into an agent representative of "decay." When the "white mold" becomes "blue mold" it is in the final stage of decay at which point it probably has already spread to other cigars. Blue mold will cause the complete disintegration of the structural integrity of the cigar it first grew on, literally eating away the cigar by a process of overmoisturization. Once your cigars become this wet, it is true, they should be thrown out.
So, while one should not be alarmed at seeing "bloom," take note of the cigar(s) that you see it on and do not allow the humidity to get out of hand in that humidor. Your cigars will be just fine.
Last but not least, although I did smoke one or two cigars with blue mold on them, it's only because I'm such a ridiculous jackass about not wasting stuff. Intellectual white college educated Northeasterners refer to it as "anal" but I have a philosophically academic disagreement with that phrase and hate the "Seinfeldians" who use it. I say "hate" with all due respect and love, of course.
Back to cigars. Keep them well, "love" them, regard them as something that requires your "care" and "attention" and not something you just bring home, toss in a box and smoke whenever you feel like a smoking stick, not caring about the taste. Being good to your cigars isn't "rocket science" nor should you regard it as a chore. Checking on your cigars, learning about your individual humidors' behavior, learning about different tobaccos, smoking different cigars, exploring your own palate's preferences and sharing your cigars and experiences with others is a worthwhile and fun hobby.