I came in and left feeling that I had nailed the interview and was expecting to receive an offer a few days later. Turns out, there was another candidate that they liked better and extended an offer to him.
After 2 weeks of not hearing back, I learned they extended an offer for this position to somebody else. After he rejected the position, they come back to me with an offer, which I gladly accepted.
I later met this other candidate and he was clearly well qualified.