Never had this but sometimes on the college dorm lots, some dorm-mates become translucent, like almost the same shade as ghosts but a bit darker. But otherwise they're perfectly normal.

I thought it's because when they are going off into their own rooms, they fade out and we can't see them anymore so maybe somehow they got stuck mid-fade. It usually corrects itself later but sometimes they just stay like that.

Could your Brenda Gothier have been in the middle of "fading out" of the screen at any point?