It's not technically a blue AE is the problem, it's a "buff/pet" that just happens to do AE damage. Same problem happens with the wizzie version of course, as well as Paladins consecrate (buff that does PBAE damage).
Not sure if they can be hardcoded to act as blue AE's somehow, but it definitely would be nice. When I am running my Pally I've really got to be careful where I fight, due to that ability kicking off.