I consider Rasmussen to be very reliable - Most Freepers do too. They prefer Rasmussen to Zogby and the Media polls. Rasmussen does monthly polls for each state. This month is almost over - I'm sure the September poll will be better for Allen. I'm sure he'll swing back. (no monkey pun intended).
Actually, Rasmussen will be polling some key states/races weekly before the election. I presume Allen/Webb will be one of them.