difficult question to answer as it really depends on so many factors...
besides you are not sure it those black spots are really fungus...
think to play it safe just send it for cleaning...
anyway, i find it funny that fungus are black spots, they usually a more like light grey streaks...
maybe those black spots are remnants of left behind by some tiny insect/s that has/have entered the lens... did you check for friendly crawlies inside the lens? :bsmilie:
Not sure about fungus and lenses...but as psychobiologist said, fungal spores are highly mobile. They can get blown all over the place if you put it anyway near your other equipment and remain 'dormant' for months to years until they have the right conditions to grow :sticktong
dump the lens in a ziploc bag and 'quarantine' it till you get it clean :think: