Skull traps "affect" ghosts

I'm a ghost and run into a skull trap. I am protected from harm, yet the chill touch still affects me. <58%hp 51%m 96%mv 4647tnl> (wilderness indoor new 8 PM) The Underdark Another blind turn! Your resolve is weakened a little more as you wander endlessly. [Exits: north west] A skulltrap goes off under your feet! You feel a horrid chill sweep through you, down to your bones. The gods protect you from a skulltrap. <58%hp 51%m 96%mv 4647tnl> (wilderness indoor new 8 PM) w The Underdark The roughly hewn walls lead you to yet another tunnel. Your hopes of any escape begin to fade away into the darkness... [Exits: east west] <58%hp 51%m 96%mv 4647tnl> (wilderness indoor new 8 PM) where People near you: (PK) Nature Boy The Underdark <58%hp 51%m 96%mv 4647tnl> (wilderness indoor new 8 PM) aff You are affected by: Skill: 'chill touch' modifies strength by -1 for 6 hours. Skill: 'herbal medicine' for 3 hours.