Bridge saddle height screws/bridge finish

I've been traveling a lot with my NYC 24/5, often down to humid climates. Have been noticing some rust and wearing away on the bridge finish, haven't paid it too much mind. But I went to adjust the bridge saddle height this afternoon and the screws wouldn't budge! I poked around online for awhile, not sure whether to use WD40, Triflow, Liquid Wrench or whatever... Since I needed to get it back up and running pretty quickly I opted to take the bridge saddles off, one at a time, and work em over with liquid wrench, rag and toothbrush. I took this photo first.

The liquid Wrench did the trick - I can now adjust all saddles up n down again. But I'm wondering if it's just a temporary fix? The screws didn't appear to be rusty to my eyes (when I finally got em out). They seemed more 'gunky' than anything. But as you can see there is some wearing away of the finish on top of the saddles and what appears to be rust forming in those places. Also I've read that WD40, Liquid Wrench and the like can actually promote the development of rust. Don't know if that's true, but if so, maybe it's time to replace the bridge saddles?

Anyone dealt with this before?

Thanks!