The lich casts spells and has an aura. The aura was a Bioware original with a duration of 1 round per caster level. If you happened to be trapped where the fear kept being started, you could be scared much longer. The auras only trigger when you enter them, so it's good tactics to stay out of them or stay in them once inside. If something like this happens again, please relog and report the defect.
I rewrote the fear aura to make the duration more reasonable. However, I don't see anything else that could have caused it. Do you remember if it was an aura or a spell the lich cast?