Trouble with Galio W

I feel like almost every time I try to wind up Galio's w, it instantly pops. 3 or 4 times already, I've tried to w> flash, only to have my w on cooldown. The odd thing is I can never replicate it when I'm walking to lane trying to test it. I know my finger isn't slipping or anything. Is anyone else having this problem, or am I understanding the way it's cast wrong? I have the impression it's just like a varus q, right?