Kassadin Glitch?

It might be just me but I have done several custom games with Kassadin just to be sure and it seems that Kassadin can glitch and activate Nether Blade while attacking a tower and after that every subsequent hit causes Nether to stay but still do the active damage over and over until the target (tower or inhibitor) is dead or you switch to a live target and it ends.

I don't know where I am supposed to submit this but it seems that here is as good as any.