Triton trailer, bought at end of season last year. It's been loosely covered with a tarp all winter. Its only used in fresh water-- no salt in East Texas ( other than on the rims of these little blue glasses ....)

I uncovered it yesterday. Its got some dust/pollen, but it also has little white spots. I'd call it "rust" if it wasnt aluminum. They didnt wash off with the power washer either.

What gives ? Should I protect it or polish it or somthing ?