Mist the snake daily during shed if you have too.

But, you definitely have a humidity issue. 60% humidity is pretty much the max for Dums. BUT a little extra during shed won't hurt. I mist my Dums down once a day during shed, from the point I see their eyes "clouding" up, until they start shedding. And depending on if I see them sheddding, I may mist them while they are shedding.
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Pat Higdon
Oklahoma City Herpetological Society Member
1.4.1 dumerils boas, 1.1 albino burmese python, 1.2 ball pythons, 2.2.1 bearded dragons, 2.2.1 leopard geckos & 0.0.1 sulcata tortoise