Nocturne E bug?

When he tries to fear you and you press zhonya's, he still fears you even thought he isnt chanelling his E after zhonya's active end.

Is this a bug? Its been 2 times today, I was playing kennen and I saw he came on me, he started channeling his E so like at the end of it I pressed zhonya's, I should have dodged that fear but after my zhonya's end I came up with a 2 seconds fear. Wthell is that? A bug or it is normal?