Another option, ignore it and just ride.
In 10 or 20 years, if you still like the bike enough to pay for a respray, deal with it then.

Those of you who wash their bikes should stop reading here. My bikes are almost never cleaned, so I could wipe a smear of grease on the spot and it'll have a protective layer of grime for a long time. Re-smear once or twice a year whether it needs it or not!

My 1933 Excelsior spent some time (If I had to guess I'd say 20+ years) out in a field on its side where the grass grew up through the frame each year, and fell over and rotted each winter, until you couldn't see the bike at all under the thatch, except for one handlebar. When I first saw it I thought it was only a handlebar — imagine my surprise when I pulled on it and felt a bike attached! That bike rides great, had it since '79 and never dealt with the rust in any way beyond wiping it with an oily rag. Yes the tubing is a mite bit thicker than your 853, but 853 is also at least a little more corrosion-resistant than mild steel.

Mark B in Seattle