At the conclusion of the February 9 2013 episode of AMC's zombie series The Walking Dead, Rick (played by Andrew Lincoln) comes face to face with an apparition of his late wife Lori (Sarah Wayne Callies), who died in childbirth during an earlier episode. Much of the analysis around this latest plot twist in the blockbuster zombie series is that it's evidence that Rick is becoming unhinged. Look at this exchange during an interview with Robert Kirkman, executive producer of the TV series,…