In 2001 I attempted to re-enter the US after vacationing abroad. I had been working in the US and had forgotten that my H1-B was expired and in the process of being renewed. At the border, I was told that I couldn't re-enter the US and I signed a "withdrawal of application for admission" form. I was told by the immigration officers that this was an alternative to being deported which would not constitute a "refused admission".
Later I got my visa renewed and was able to re-enter the US. I am now a permanent resident.
What should I answer on official forms that ask "have you ever been refused entry to the US"?