Sivir Boomerang Blade Bug

Occasionally my auto attacks would be boomerang blades instead and would put boomerang on cool down or use mana. Whenever I would use boomerang blade my next few auto attacks became boomerang blades as well on top of the random other boomerang blades I had.

1. It was solo ranked and I picked Sivir.
2. Teams were: Shaco, Cho'Gath, Sivir, Lux, and Blitzcrank vs Thresh, Annie, Ashe, Gnar, and Vi.
3. Starting items were dorans blade, 1 health pot, and warding totem.
4. It was Sivir and Blitzcrank vs. Ashe and Thresh.
5. I picked boomerang blade as my first skill.
6. A few auto in on minions I noticed one of the auto attacks was boomerang blade instead.
7. After I used boomerang blade for the first time my next two auto attacks became boomerang blades as well.
8. All of my auto attacks seemed to use 2 or so mana as well.