Apparently this wasn't really a "push poll" but more likely the "push poll" evil twin "message testing." Push polls are usually only a few questions long, this poll apparently lasted 20 minutes. "Message testing" is similar to push polling but because the message test questions are buried in 20 minutes of polling the effect is minimal. Campaigns use message testing to test out how various lines of attack on other candidates would work with voters. In this case, Mitt's Mormonism was the target.
There are also whispers that this message testing was done by Romney supporters. It wouldn't be unheard of for candidates to message test themselves to find out their own weaknesses. However, given Romney's *shock* at the line of questioning if it turns out to be his people behind it he'll look like a total ass.