The plan is to add a "notify subscribers?" option when creating a new profile post or editing an existing episode. @ck_tapastic is correct that the little red bubble shows when you've "said" (i.e. posted) something on your wall, but if people are only interested in the comic itself it's easy to miss. Once we add the option to notify subscribers, creators will have to be responsible about how they choose to use the feature... as many fans/readers already complain about getting too many emails and notifications (just from new comics they subscribe to, for example)!