Under normal conditions, the Mother would be pleased that the Avatar recognizes her status, even in just such a word as "wow."

But these are not normal circumstances today. It's not normal anything.

"They have come here before you." If Korra already knows of her previous two lives in existence here, there is no reason to hide it. "But they could not explain to me some of the things that I would most like to know." Her tone sharpens, darkens. "For example, what you have done in this place and this time, allowing the world of spirits and humans to collide as they have not in ten thousand years."

The Mother of Faces gets right to the point.