Bluegill spawning in October is highly irregular. So are bluegills spawning in September for that matter. Normally high water temps make a spawn in August not very feasible and since daylight tends to wane quickly starting in mid September, fall feeding patterns start about this time and not another round of spawning.

Females having eggs and fishing being on nest is different from an actual, successful spawn. Sunfish females will create eggs as a rule once sexually mature and water temps and daylight duration are right, but will abort or absorb the eggs if conditions are not right or if they have spawned more times than their bodies can handle. Not only that, but sunfish fry that are hatched this late in the season tend to have a lesser chance to survive the colder months. After droughts, floods and other nature events that negatively effect the spawn, nature normally throws a lot of numbers for the next spawn, so maybe the late summer spawn will be that case for this spring, but from what I have seen that is the exception and not the rule.