It’s not good but it’s not so bad either.
The running edges of the rail where the balls roll are the key faces for accuracy and bearing life, those are kept lubricated by the oil you put in the bearing blocks to keep them lubed properly. I track this by occasionally wiping the rails clean, jogging the machine and then checking that there’s a slight film of oil left behind by the bearing blocks on some white tissue. When the blocks stop oiling the rails I re-oil the blocks, takes a few minutes with a small syringe, There’s some rail care instructions from Luke on the forum here.
If your rails are still shiny and rust free then maybe just give them a periodic cleaning and then wipe down with a sponge applying a little of the Mobil Vactra way oil to make sure that any exposed areas not lubricated by the bearing block have a good oil film to protect them?