Missing legs after molt. Orthoporus Ornatus

[Diplopodia]

One of my Giant Sonoran desert golds disappeared for 5 weeks and recently made an appearance alive and well after what I assume was a molt.
It's missing several sets of legs and has some nubs on its back end now.

Is this from a bad molt or something I've done?
Could it be I'm keeping the enclosure too damp for the species? I don't keep it as damp as my others but I'm always afraid to go more than a few days without adding moisture given I live in a desert climate myself.

 

[Elytra and Antenna]

Adult Orthoporus do not molt. Orthoporus do lose legs if they are kept too damp, but sometimes from just being old.

 

[Diplopodia]

Good to know. Thanks. It's impossible to tell how old they are given they don't breed in captivity. I know the species can grow upwards of nine inches and this one is currently between six and seven inches. Wouldn't it be possible that it still has a molt left? I've only kept these for two months now. I bought four. One of them recently died. I found it on the surface lifeless. That one was fat and right around nine inches long.
There's one smaller, about 5 inches, and thinner than a pencil so I expect to see it grow. When I first got them all four were active on the surface then shortly after all but the smaller one disappeared. Right now, I have two active ones and the other is still nesting going on six weeks.

 

[Diplopodia]

Adult Orthoporus do not molt. Orthoporus do lose legs if they are kept too damp, but sometimes from just being old.

I have Millipedes in Captivity by Orin McMonigle on a list to buy. Is Giant Millipedes: The Enthusiast's Handbook different? It's written by the same person but sells for half the price.
I'll probably end up buying both. Thank you.

 

[Elytra and Antenna]

I have Millipedes in Captivity by Orin McMonigle on a list to buy. Is Giant Millipedes: The Enthusiast's Handbook different? It's written by the same person but sells for half the price.
I'll probably end up buying both. Thank you.

The first is a larger hardcover from 2012, the second is small, stapled paperback from 2005.