You can pretty clearly see the white mold over the dark patch. This leads me to believe that more likely the dark patch was from surface drying or becoming like jerky. This is common in dry aging and can be more pronounced in refrigerated drying as the average humidity in refrigeration is generally in the mid 40% to maybe 50%.Sorry, I forgot to respond. I'm sure you wouldn't take an actual whiff of it lol, but I guess you could describe it as earthy or musty.
Anyway, I'd trust Eric on this. White, surface mold is common when doing a true dry cure, but as he said, it's rare for this to happen under properly held fridge temps. Could there be some condensation in those drawers?
Perhaps someone likeindaswamp could offer you better insight?
I watch for this and sometimes bag on day 10 or 11 if I feel it’s getting to dry on the surface. In dry aging steak for example, once finished they will cut their steaks off of the primal and then trim the dry rind off, that rind can appear very dark even black.