Hey Joe,

I'd have to see the course completion criteria on the courses completion tracking page to be certain, but off hand I think its worth mentioning that course completion are run off of the cron and aren't instantaneous. If you have your quiz ticked under the activities completed heading (Settings Block > Course Administration > Completion Tracking), and to be safe set the activities and overall aggregation methods to 'any'. Then the course should be automatically marked as complete on the next cron run after the quiz is completed.

Hope that helps
David