Iron(II) oxide on stainless steel? I noticed after some use that a stainless steel spoon that I have started forming $\ce{FeO}$. Stainless steel is not supposed to rust like this. I don't know of any black iron hydroxides, chromium oxides, or chromium hydroxides so that lead me to deduce that it is Iron(II) Oxide.

But why would stainless steel oxidize? I mean it does not make any sense since I was told that stainless steel does not oxidize.

And how can I get rid of the oxide? Putting the spoon in phosphoric acid perhaps since phosphoric acid is a really good rust remover?
It was probably a poor grade of stainless steel. The chromium oxidizes before the iron therefore you obtain a thin layer of protection. In poor grades of stainless steel, I have seen rust form over a period of time or during exposure to non ideal conditions such as high humidity. This is probably because the manufacturer added the minimum chromium required to meet standards, and so you get a smaller ensemble of chromium oxide and more iron oxide. 

You can treat the metal with phosphoric acid to remove the rust. You can also treat the stainless steel with concentrated sulfuric acid to produce a phosphate layer for additional protection with minimal loss of material (they do this in industry)