invis removal

Guessing this is by (bad) design. Just checking, since I've never had it happen before. (prompt) whe A trampled trail in the foothills [Exits: north west] A disgruntled Whitecloak mutters to himself quietly. A disgruntled Whitecloak yells 'Darkfriend in the camp!!' You yell 'Help! I am being attacked by a disgruntled Whitecloak!' You dodge a disgruntled Whitecloak's slash. A disgruntled Whitecloak is in perfect health. (prompt) People near you: (PK) MeMeMe A trampled trail in the foothills A disgruntled Whitecloak is in perfect health. (prompt) flee A trampled trail in the foothills [Exits: east west] You flee from combat! (prompt) aff You are affected by: Spell: 'invis'.