[GAMEPLAY] Darius auto-attack bug after W+Q

During a Summoner's Rift game yesterday on Darius, I found an auto-attack bug. I thought it was random at first but I seemed to be able to reproduce it when I performed this sequence of events: AA + W + Q. Any subsequent AAs would halt, almost like I hit "S" to stop. Darius would just stand there until I right-clicked or move-attacked again. This happened almost a dozen times in a single game.

I will attempt to test it more today to figure out exactly what's happening.

EDIT #1 to include [GAMEPLAY] in title.