There is skills ghosting in pve for sure, and perhaps it happens in pvp with a lot of latency I don't know. But so far I have never really had to complain about this in pvp except for this.
In this case I seriously suspect the same usual suspect, Miracle of Nature. I cant say for sure it's possible with stuns. MoN had a lot more leeway for it to happen before 7.1 than actual stuns, perhaps due to the character transformation.