I noticed this just now that when I am walking in towns quietly or in an area that Zombies are normally not found one or two zombies will start chasing me full sprint and chase me down in which I can not shake them. I thought this was something I did at first because the first time it happened I was chased out of town turned and fire my pistol at them they went down, mind you I was a good ways from any town, buildings and main roads when I fired and 2 more popped out of the distance chasing me. Like I said I thought maybe it was me but when I respawned in the middle of no where I was gathering my self then 2 zombies out of no where came at me full sprint again... then I died, then again as I was approaching a town after I had spawned.