Elle — I don't have a cerakote TPB, opting for the raw bar earlier this spring, but I also live in a pretty dry climate. Your post had me curious though.
Have you run across this post by Two Rep Cave? If you live anywhere in that god-forsaken 2/3 of the country east of the Rockies where there's that awful thing called humidity, you just might get that discoloring. My initial thought, confirmed in the post, is just run a nylon brush over it. Anything stiffer will start to scratch (and remove) that coating.
Perhaps a quick wipe with some isopropyl (not rubbing) alcohol after you two finish your session will help.
Bill