Board Thread:Questions and Answers/@comment-10797017-20130622101437/@comment-8986886-20130708183418

In the Fullbring Arc, Ichigo used his Getsuga against Ginjo, while Byakuya, Renji, Rukia, Toshiro, Kenpachi and Ikkaku were watching. Neither of them seemed surprised or made any comments on Ichigo being able to use the technique.

I think that at least Rukia, who used to train with Kayen, would have recognized it if it was a Shiba technique. :)