I imagined that the worm itself would be a very high quality of stainless and unlikely get rust spots but not so.
Being a Chinese made, mass produced mount, though the worm will be stainless steel, I doubt it would be high quality 416 or similar. A lower grade stainless in normal conditions should still be resistant to corrosion ( rust .)
The condensation that you noticed is certainly not something that would happen in normal operating conditions, thus the squeaking and the corrosion. The TLC you've given the mount will keep it in good shape for a long while.
