Roll20 tried that for about 1 week, then they rolled-it-back and removed that feature. Shouldn't be doing it anyore. It stopped about 2 weeks ago or so. Have you had any posted more recently, like this week? If needed you can go back, as GM, and manually hit Delete Delete Delete on each thread that was posted during the time they livetested that idea. There are a few threads about it, if you want to go back and give Roll20 your feedback on the Game Reminder and Scheduling features, as they will probably try again on this area.
