Roommate left bread out for two weeks: could these mold spores have gone airborne?

Yes, but. Unless you have a specific and rare allergy to that mold there is no risk. Mold is an ubiquitous organism with tens of thousands of strains that you are exposed to every day of your life in one form or another. It is outside in the air, on trees, in the soil. The stuff that would grow on bread is not particularly toxic.