Mould inside homemade coldframe?

I made a coldframe as a winter project from an old wooden cabinet - its been sat outside on the patio for a couple of months now and I've seen recently mould has started growing on the inside.

Would it still be ok to use the coldframe? Or would the mould spread to any veg I plant inside once I move the coldframe to my allotment? I guess the mould suggests its stays rather damp inside.

I was thinking of growing courgettes inside.

Thanks!