Wouldnt the condensation be more systemic on the walls if it were the result of air humidity? My enclosures are very well vented and i still get condensation underground, granted, his is a couple inches up, but it is so concentrated in one placeBeing completely honest, IMO exuvia check is the way to go, man. I don't venture in ventral sex... I don't trust my eyes that much, especially at a certain hour :-s
Are you sure btw that you provided enough ventilation to your P.muticus? I see condensation... not good.