I vote a loose ferrule as the most likely cause of a rod break at or next to a ferrule.

5. UNSEATED FERRULES

Another easily avoided rod breaker is an unseated ferrule, which is like a time bomb, says Johnson: ?It?s an almost surefire way to break a fly rod.? ?The ferrule sections loosen up during casting, and if a fisherman does not reseat those sections, they will eventually break,? warns Jim West. ?It happens all the time.?
If you are casting weighted flies, sinking lines, or a Spey rod, it?s imperative that you check your ferrules regularly. The constant stresses and twisting action of casting will inevitably loosen those fragile connections.


http://americanangler.com/technique/busted

Improper Seating of Ferrules

Multi-piece rods come equipped with flexible ferules to give the most uniform action. In order for them to perform, they must be securely seated. Loose connections will give a ?wobbly? feel when casting and can possibly break from the inside out.

http://www.sageflyfish.com/blog/04/2...-by-joe-mahler