Graves Q exploding bug

So i just played a game against graves jungle and 9 out of 10 times graves used his Q after it exploded there is a visual glitch that last about of minute and its basically graves Q exploding over and over and over again non stop for a minute. while this glitch doesnt to any dmg, the visual glitch is confusing because i cant tell if graves is still in that bush firing his Q of if its a glitch, so i have to stop to watch for a good 8--10 seconds to be able to tell if graves is really there or just the visual glitch again.

i dont know exactly how the glitched work as far as i could tell

1. Graves uses Q on a enemy champion
2. both parts of Q do dmg to enemy champion
3. visual glitch of graves Q going off ever 2-6 seconds even if graves is dead or on the complete other side of the map already