Diana Bug?

Encountered a bug while playing Diana that made playing her considerably more unfair for my opponent. While Cs'ing I was trying to only use the passive when I needed it and not shove wantonly. I waited until just after my passive faded to cs, and my passive still went off. However, the proc still counted towards the next passive, meaning I had only one more auto before my next proc/cleave. So in practice, and it isn't hard to do at all, you could get it off every 2 auto attacks, no I didn't have sated devourer, this was a midlane game.