Some argued that it was an outlier. Well, they may have been right. The pendulum has swung back.
There's a graph tracking the ups and downs of the polls on this issue here as well as this bit of speculation:
The recent dip in pro-life support could be a response to the recent assassination of late-term abortion provider George Tiller. It may also speak to the passing of the Obama-at-Notre Dame controversy, which revolved around the president's and the Catholic Church's abortion stances.
I'd put more credence in the first notion. Sensible people suddenly saw what the rightwing nutbars had wrought and they're bailing.
May it continue and accelerate.