How so?

The top comment on Reddit says:

"As a casual player of Go myself, some of the moves that AlphaGo made were crazy. Even one of the 9th Dan analysts said something along the lines of 'That move has never been made in the history of Go, and its brillant.' and 'Professional Go players will be learning and copying that move as a part of the Go canon now'."

There was one move that literally caused the 9th dan commentator to do a triple-take. It apparently turned out to be super effective.

Specifically, move 37 at O10: https://youtu.be/l-GsfyVCBu0?t=1h17m45s

that link doesn't work for me. but these do:

http://gobase.org/replay/?gam=/games/inter/matches/AlphaGo/L...

https://gogameguru.com/alphago-races-ahead-2-0-lee-sedol/

Not only did the commentator do a triple-take, but the next white move took Sedol about 15 minutes.

One interesting thing that happened during the time for Sedol's next move was that the 9th dan commentator started referring to AlphaGo as "he".

Yeah, I've been noticing the pronouns thing. In chess challenges I always got the impression that the AI's play style was like a chain chomp. Limited, but ruthless within its limits, and definitely 'mechanical'. In these games the commentators are treating AlphaGo like a person.

I might be imagining it, but I think this has been increasing with each game.

That did not happen. He played a few unexpected moves but this games would have little to no impact in terms of modern Go theory.

Other than the kake(shoulder hit on the right) the game might have been a regular top-prop game.