Rusty Tool Mystery

Okay, I’m perplexed.

I control the humidity in my shop and it does not change very much  and not much has changed in the layout of my small workshop.  The only new addition to the shop has been a new small electric crock-pot I use as a glue-pot and it seems to give off less steam and humidity than my previous one.

For reasons unknown to me all the tools stored over my bench have become covered with a solid patina of fine brown rust. This includes most of the tools I use every day.

Rust

I know how to remove the rust and I know I can give them a light coating of cammelia oil or wax to prevent rust from forming again.

What perplexes me is that after working in the same space for several years under more or less the same conditions this is the first time I have had a rust problem in the shop.

Luthiers, Woodworkers, Mystics, lend me your ears!

Tools in other areas of the shop are not getting rusty; it only happens to the tools over the bench that I constantly use!

Anyone have an idea of what may be going on? Am I missing something that may be causing this?

Thanks!