Bug or Feature?

I had placed one of my new quest NPCs in a location.  Not just any location, I had placed it in a specific location.  I was a little dismayed when I later returned to this NPC and discovered that it was gone.  I found this troubling because this was a stationary NPC; it did not walk around like the St'ple sisters.  A quick search revealed the NPC in the same area where I had left it, but it was far from where I had placed it.

This was puzzling.  How did it move?

I ran a couple of tests and discovered that certain monsters had pulled the NPC away from my carefully selected area!  I reviewed the scripts and, after a lot of ferreting, found the section of the code that enabled monsters to pull NPCs.  Now comes the delicate part: applying a fix that does not break anything.  The idea of monsters having the ability to pull NPCs is kinda cool, so I am hesitant to completely eliminate it.  I am currently working with the other GMs to apply a flexible patch.

Sometimes I am amused on what bugs get unearthed through play.  Or maybe it's a feature.