It's a point that after one prior accident it should make her a safer diver and pay close attention to air supply, or it could mean she did not learn the lesson and got herself into the same situation, we don't know. With one prior accident we don't know, if she had two then a reckless pattern would emerge.
Still, running out of air is high on the list of possibilities as we know she was very involved in trophy lobster hunting and could have been distracted. Another possibility high on the list is runaway negative buoyancy with subsequent narcosis.