Replying to Moldy mitts

I had a quick look but i'm pretty sure nobody's posted about this happening before. After a dry slope airbag session last week (England sucks) I cleaned off all my gear and packed it up as usual and all seemed fine, yesterday however I go into my bag to find my mitts covered in fuzzy white mold, luckily it was only on the outside but it was fucking disgusting.
I immediately washed them thoroughly with dish soap, and then bar soap until all the mold was completely gone. My plan is to re waterproof them once they're completely bone dry.

I've only used these just over half a season and I do the same thing whenever i'm on real or fake snow. Nothing like this has ever happened to anyone I know either but this was my first day on a dry slope so maybe that had something to do with it?

Has anything remotely similar happened to any of you guys or know why it might have happened? any suggestions of what to do would be really appreciated too as getting new mitts is spenny and definitely a last resort.