It’s not a technicality. He did not share the contents of the memos with the N.Y. Times until the 15th. That is what he testified to today. Someone else was the basis of the story on the 11th.
When were the memos (allegedly) created?
We do not know the source of the leak on the 11th, and given that Comey has admitted to leaking material (to a go-between) he may well have been the source on the 11th through the same devious channels.