Fizz E Bug

This was an interesting bug. Since I do not record my games, I will try and describe what happened. I was playing Fizz and a teamfight erupted. I q'ed into the middle, but quickly e'd out. Later on, I tried to E away, but was unable too. I survived and thought I must've misjudged my cooldown. Yet whenever I pressed E after, the spell would not cast. I triple checked and made sure the spell was off cooldown, but it never worked. It only started to work a minute later right after I q'ed through an enemy Ahri. Not sure if this is repeatable or not.