yeah the way I took it was that she must've read some of his works in the past and didn't realize it was him this whole time. but who knows maybe its something elseWhy did Nodoka became flustered when she discovered Sensei's real name? Is it something to do with how Akira used to write before? Now that I think about it, he's technically considered a genius and was top of his class.
He might have done a book signing before like Nodoka.