My sources confirm it was an aneurysm.
For those who are not familiar with the term, simply put, it is a situation where the wall of an artery weakens and "balloons" out. It is not a problem until it ruptures, then you can bleed to death.
If it is in the arteries of the chest or abdomen, you bleed to death,if it happens in the head, you USUALLY don't survive or have long term deficits/effects.
These are not usually detectable on normal exams by your MD, they usually have no symptoms until they are about to rupture or have ruptured.