Seems the possibility to retrieve deleted/removed posts and the no notification/message receive, I guess the thread wasn't deleted, just moved to some board only mods can see and retrieve (correct me if im wrong though).
Yes. The thread would have been moved to trashcan upon which there would be no notification that the thread was deleted. Threads are moved there for this particular situation as it is possible to reinstate threads which are moved there, but only certain mods or the admin have this ability, IIRC.