Mold on clothes and shoes

Since April of last year I haven't spent much time looking at my clothes or shoes (been pregnant, then post-pregnant - meaning I've spent a lot of time in maternity clothes and yoga pants and very comfy shoes). Today I decided to have a good look at my closet and found MOLD on a number of hanging items as well as on some shoes - in 2 different closets. It looks like white mold. The closets are dry and the stuff was hanging (and the shoes were on a shoe rack). Where did this come from? Should I be concerned that we may have a mold problem - and if yes, what do I do (one of these closets is in DS's room)? Will dry cleaning take care of the mold on the clothes (they are dry clean only)? I wiped the shoes down with a clothe with eucalyptus oil and that seemed to work.