I went into a motorcycle shop to find a can of chain lubricant. Then I waited until the other customers had left the shop and paid for it.
Very carefully avoiding access I sprayed a small amount of it onto the bolts and washer. While softly depressing the nozzle I held a rag underneath. Then I wiped the access off. Next morning I again wiped the bolts. Just to go sure, I also wiped the rotors with a rag and brake cleaner.
This may help preventing the spring steel from rusting.