It's just going to be surface rust, if you're worried, take them off, clean them up using a product or two from Bilt Hamber (Deox Gel) - then coat them in a spray wax like the stuff from toolstation, or get something specific that'll prevent rusting again.
Once again, Bilt Hamber might sell something or Frost.co.uk are worth calling to ask.
MeisterR sell this: https://www.meisterr.co.uk/products/meisterr-arc-anti-rust-coat/