You were just the victim of an ambush. Apparently Ayessa Dawnsinger was not exaggerating when she said that she would have vengeance for the Windshaper lives you took on Zephras Isle. If the Windshapers are sending assassins after members of the High Order, Elaadrin Evengale will want to know about this. He should have arrived in Dalaran by now, so you should check in with him there.