I MENT if the spell was casted on groups foeld of vision, and as she got spooked by Aliesa, Aliesa might.have notices it and allowed to make perception roll to notice casting. (Unless of course there was no somatic component needed.. ) and no, Aliesa has no reason to cast.detect.magic.. given the number of bards (illusionists and minor weavers) around...detect.magic would do no good anyway (too many auras)