Zombies see very far...

I just recently started a new world in survival mode on easy, everything was fine at first until I updated my snapshot from 13w25c to 13w26a.It's night time and i'm outside of my little shelter I built, in a lit up area. All of a sudden tons of zombies start rushing at me. i see one I kill it then I turn and kill one behind me then theres another behind me again and then I finally kill them and turn and look around and see zombies every zombie I could see looking and me trying to get to me.Although last time I checked they can't see you from that distance...not even close.