**NOTHING **that a Pope says is ex-Cathedra unless the Pope makes this distinction absolutely clear at the time.
It is possible that the Ordinary (or Extrodinary) Magesterium may later formally define a particular Papal statement as infallable, but that is not ex-Cathedra (which, by definition, must be defined as infallable by the Pope himself).
It is extremely rare for a Pope to teach ex-Cathedra. Pope John Paul II, for example, never once taught ex-Cathedra, even though he reigned far longer and wrote and said far more than most popes.