You don't appear to be banned according to your user info, but it's possible that you tripped the automatic flood-ban for making too many comics in a short period of time. If that's the case, you might have to wait a couple days for Brad to unban you.
Also, none of the moderators has taken credit for deleting one of your threads, so is it possible you tried to post a thread after you got auto-banned and it didn't show up?