This is hilarious. I played for like an hour or more and was ready to leave the mansion to the garden shed and get rid of Forest Speyer for good and a zombie was in front of the exit door like one normally is so I blasted him with the shotgun not realizing it was him lol. It makes sense though considering it's the last time you'll see him I just didn't think about it. I'm guessing this must have happened to a lot of people.