Diana Q Bug or hitbox problem

I was playing against a Diana in the mid lane a whilst back and I noticed that even though her arch hit me I received no damage but oddly moonlight was applied. Even in a team fight the Q hit 3 of us but same thing happened no damage but there was moonlight applied on us. There would be times where the animation showed it hit or grazed us but the damage didn't apply. Has anyone else noticed or experienced this? Even if this isn't fixed or that big of a deal its helpful for me really I don't get combo'd lol.