We never did ask where the spokes were breaking, but assumed it was at the elbow.
All of the other spokes have gone through the same number of fatigue cycles, although some probably weren't "over stressed" as much.
Keep in mind, 3-4k miles probably isn't that bad for a machine built wheel.
Before rebuilding with this rim, make sure the brake tracks have enough "meat" to justify.
Lay a straight edge across the brake track and see if it is concave. If you can see daylight.....
The point about having the tension checked on the rear (and new front) is very valid. If the wheels had been properly tensioned when new, you'd probably still be riding them without issue.