Sure, but a little rust because they weren’t used isn’t a problem, comes off when you use them, but is an instant fail.

All brakes rust when not used. If you drove around in the rain today, then didn’t drive for a few days, you’ll probably have a little rust on your brakes. You go for a drive and then it’s gone.

If you take your car in for a pre-inspection report, and they see some rust on the brakes, they will tell you to drive it around a bit using the brakes a lot before taking it in to be inspected.

it’s not an actual problem.