Well, it's not hearsay - Gozo Shioda put the story in writing in "Aikido Shugyo" (page 189), and he's quite clear about having seen it with his own eyes.
Whether or not you believe him is another discussion
The fact that you might believe it true because Shioda Kancho said it is, is exactly what makes it hearsay.
I have heard many things said that seem to be much the result of "selective memory". For instance, there are others who have said that O'Sensei could literally disappear from one spot, and instantly reappear on the other side of a room, without anyone seeing him en route. There is too much scientist in me to simply accept these accounts at face value, as I recognize that what makes it real to those giving the accounts may be as much a result of what they believe, as it is what they might actually have seen.