This happens to me fairly frequently, usually on world bosses or higher health wardens quests. And its not just since 7.2 either.
Its never, happened in raid though.
I will pop my cooldowns and notice that there is no cooldown on kill command, that i can just spam only KC and they go off, with no cobra shot or DB/DF in between.
The damage goes off, the global cooldown begins and I see the damage on the screen.
I cannot recreate on demand though.