Why did my champ turn around?

Hi, I was playing {{champion:497}} today and this happened: http://plays.tv/video/59a1f00e71ddfa38fc/- So basically, I kept clicking towards Kog'Maw to do the leap with 'e', but when I got silenced by Cho'Gath I turn around. What is the reason for this? Is this a bug?
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