I have a group of gilas, they are kepted on a dry substrate with heat cables at one end for heating (also kept in a heated room).

They have a large rubbermaid type box with an inch of water in and tend to spend 80% of their time soaking in this hide / water tub.

Will this cause a problem or does this 'high humidity hide' copy the natural high humidity of the burrow systems they use in the wild?

They appear 100% healthy and feed every meal offered, they are quite active at night.