This has gone unanswered for a long time. I don't know the answer, but someone on the harvest forum may? I would re-post there if you still have them.

I hesitated to answer this as this has never happened to me, I'm thinking your beans weren't dry enough before putting them in plastic bags. The bean seed I harvested this year which 'look' dry will stay in their wicker baskets air drying until about January only then will they be packaged up for storage. Here any bean seed that appears to have mould on it is tossed. You could try rinsing and drying them, do a germination test on a few, if that works air dry them for a couple of months, keep for seed, I wouldn't eat them. If they are an easy to find variety I'd just toss them and start fresh next year.

Annette