Xerath Q bug [Gameplay]

Last two games I played with Xerath mid. I had an issue while casting Q. Charging it near the first tower would cause Xerath to anchor in place through the duration of the charge. I'm not sure if others I was playing noticed it as they wouldn't give me information when I asked. Could not replicate it anywhere other than around mid tower. at first I thought it was when near enemies but that doesn't seem to be the case. I was playing topside this last game. I don't remember what side I was playing the previous game.