Gitch/fluke with Fiora lunge hitting too hard?

While playing in ARAM against a Fiora, her items were Ghostblade, Hydra and Last Whisper she hit me with a single Lunge for 1800. No unique circumstances. It was an insta kill. Now I've played Fiora and her lunge can hit pretty good, but nowhere near that good. This happen to anyone else other than me? If so how often do these glitches in the matrix occur?