Is this shaman distance attack a bug?

I fought a shaman at least 24-72 hours before to this. I saw nothing in my effects list, I was indoors, and to my knowledge he was not in the area. The healer closes his eyes for a moment and nods at you. Your body shudders, and you feel fully refreshed! With a thunderous clap, a bolt of holy energy emerges from the ether and strikes you in the chest! Shaman's divine fury MANGLES you! *snip*