The tubers are fine, probably, so don't worry.
Storage mold comes from humidity and poor air circulation. You need to dry the tubers adequately, maybe put them on a tray in the living room for a few days. When they have dried adequately store them in dry peat in trays or even in plastic bags. It is the dry medium that is important.
You could also use the saran wrap method which takes some work. The bleach solutions suggested above would help, but you need to dry the tubers. Even if they get a bit dessicated you can grow them back even from pretty shrivelled. I have a very long growing season so I can afford the time, but it is time lost. However this sets them well back, and you are better to keep them plump by the occasional spray and them back in the peat ( perlite or vermiculite).
If you want you can pot the tubers up in pots with a mix of new compost. Don't water the mix in the pots with the tubers. The mix will be damp enough, and it does not matter if it is a bit dry. Store them in the pots outside under cover where it will not rain on them, a car port or similar, or inside in an unheated place.
Mainly don't worry, dahlias are as tough as potatoes.
