Hi Sam! Is it MOLD-like green fuzzy stuff-or is it white? I made the mistake of confusing mold with the harmless white-stuff. It's actually salts and stuff from the stuff in the soil & the water (am i getting too technical here for ya? ) If it's the white stuff, you can just water thoroughly a couple of times and it should wash out. Hope this helps, and hopefully, someone who knows a little more than me will be by soon. Good luck to your friend!

sam, if it is indeed mold, then she isn't letting the soil dry enough between waterings. if the soil was compacted and/or the plant root bound, then she probably didn't do it any favors by just top dressing it. sounds like it is time to either pot it to a bigger pot, or root prune it (something i am not fond of, but understand the need for). also, some philos put out something called air roots. that is a different ball game all together.