I don't know what it is but the first episode of every season is always terrible. I stopped watching the show entirely because of how bad season 2's first episode was. I got back into it tho and know that this is just how Walking Dead is. I'll stick with it.
EDIT: Season 1 actually had a good first ep. Two, Three and Four.....not so much.
Will make predictions for credits. Please, I'm so broke.