I'm no expert but it looks like the mold you get in damp conditions. It may not be deadly to the plants, but if it was me I'd remove the leaves as soon as I saw anything that resembled the sort of mold/dampness that I'd expect to see.

Mold usually has a "damp" smell about it, because in damp conditions we smell mold (and thus associate the smell of mold with dampness - i think ), does it smell like that?
denial102 Reviewed by denial102 on . please tell me this isnt mold!!!!!!!!!! can someone look at these pics please. on some of my leaves it appears to have small white circular patches on the leaves. ive seen these patches for some time now and nothing has changed. ive rubbed on the patches and it barely came off still being there. the plants are in about 30days of vegetation. im just worried cause im almost ready to throw it in the 12/12 cycle and i dont want my bud later to turn into mushy mold. soil-ff ff nutes indoor any other info you need ask me, i Rating: 5