Shit like this happens all the time. Pretty sure that the higher your latency (ping), the more likely you are to see it.
It basically comes down to a race between your actions and those of your opponent. The lower your latency, the smaller the window is for overlapping actions and the resulting weirdness you saw.
In NA, the east coast ping is roughly double (80msec) that of the west coast. I'm on the east coast and have often seen an ability go on CD, with no effect, just as I die to an opponent.
Riiiiiiiiiiiiiot... Give us those east coast servers. This is going to be a real problem, since the game is becoming more and more twitchy.