Hand wash them.

*gasp*

OP - do you use dishwasher detergent that has citrus in it? If so, that is probably what is causing the spots. We had this problem, and so did my in-laws, and it went away for both of us when we switched to dishwasher detergent that did not have citrus.

I can't remember the reason why, but something about the acid reacting with the steel. Maybe google it, this is how I found out initially.

Op here. Thanks for the suggestions. It does not seem to just happen with knives. It also happens with regular stainless steel cutlery- forks, spoons, etc.

Don't put it in the dishwasher.

Good quality knives do get a bit of rust from time to time. I'm able to scrub it off. I think good knives have a bit of carbon in them which leads to the rust. I also very rarely wash my good knives in the dishwasher.

This TOTALLY NORMAL and has to do with the finer grade of steel used on the blade than on the handle or the rest of the silverware (the blade is a different grade so that it can be sharp enough to actually cut things...). It helps to wash all the knives together and separate from other utensils (if your silverware holder is divided into 6 compartments or whatever, just pick one that is for knives). If you get spots, a tiny bit of Bar Keeper's Friend will take them right off. I don't wash my knives separately (my husband can never remember where they are supposed to go), but give them the BKF treatment every few months.

stop washing them in the machine?

i think it's time to replace them. you can't seal or flake off rust.

First, what can I do to stop it from keep happening?
And second, how do I get rid of the spots already there?
Thanks.