Sandman -
Good luck hunting.
I'd be curious to know if the deer seemed to lay off your neighbor's alfalfa? It seems that the deer on my neighbor's alfafa have switched back over to clover - good for us. We've noticed this trend three years straight, after the first frosts. Sounds like you might have a similar scenario.
My father-in-law is an old timer, and he always said the the alfalfa gets "bitter tasting" to the deer after a frost. I don't know if this is true, but I must admit that the deer behavior tends to back it up.
Good luck with you plots and hunting.