More than you wanted to now about stainless steel, below - Yes, there are a BUNCH of different "grades" of SS. Some of them rust, some of them don't, depending on how much chromium in in the alloy mix. Some can "corrode" to whatever is mated to them, as Mike inferred, but sometimes that corrosion can be dendritic growth (crystalline structure that forms a chemical bond between two surfaces). In your rainforest climate, the anti-seize makes a lot of of sense, if at the very least as an insulator between the two parts.
You getting hit by the storms we're hearing about, headed your way?