The woman, naked apart from a woolly hat, sprinted on to the field in the second half as the All Blacks prepared for a defensive lineout. Running from behind the All Blacks' try-line, she made it to Argentina's half before security eventually stopped her.
One guard, from the Red Badge company, appeared to make a high tackle on her as she lost her footing.
After several minutes she was led from the field amidst a group of security guards.
Hansen said security at tests had to be more aware of the potential threat from pitch invaders.
"The question is, how do they get on? There was enough of them in the jackets, you'd think they'd be able to stop them," he said. "They did really good tackles at the end of it, but they probably should have done something before she went on."
Asked if he was concerned about pitch invaders, he said: "You've got to be, don't you?
"They're just a pain in the backside."
Captain Richie McCaw didn't appear overly concerned by the incident, but early in his career he was involved in a more sinister event when South African Pieter van Zyl scaled a fence and disrupted a match against the Springboks in Durban in 2002.
A drunk Van Zyl, incensed at referee David McHugh's decisions, tackled him and dislocated the Irishman's shoulder.
McCaw helped wrestle Van Zyl to the ground.
"I'm not sure we were worried about that tonight, but I know what you're saying," McCaw said when reminded of the incident.
"You don't really want to see that to be honest. It might be a laugh for some, but you don't really want to see that. I had to try to focus on the next lineout which was a bit difficult."
- By Patrick McKendry of APNZ in Napier
