VI got in trouble so she's grounded bug

>playing JG VI >ganked Cassiopia >activated my Q simultaneously as she activated nasty ground spooge >I only caught the very edge of the effect and was grounded for only a fraction of a second and then I was out of it >Q stuck for the entire 5 seconds of windup time I was sitting there not able to cancel Q or do anything else >tried to recreate the event several times but it seems that she only gets stuck when both skills are activated at the same time