A bad sample because of Halloween?
1) Married people and parents trend Republican.
2) Among adults, it's almost entirely parents who are out on Halloween. (A Saturday Halloween would have more twenty-somethings at parties.)
3) I'd bet parents are also over-represented amongst those who are hosting trick-or-treaters.
4) Group 2 above (and to a lesser extent group 3) were not answering their phones in the early evening hours.