I never book that far ahead with credits on AirTran. In looking around, the availability does look strange and limited on that route--I hope it isn't a trend. Nonstops are limited for months prior to November. October (?) is sold out for coach awards. On the plus side, a $108 OW fare looks widely available; I usually don't use a coach award unless the fare is over $200.
One advantage with AirTran is that the "high" award ticket actually gives you Business Class, it is wide open unless you are talking about Thanksgiving.