They're not that unusual in aluminum, which has a talent for memorizing distortions. If the former, the bends will remain when the shrouds are slacked completely, and you might consider having a little conversation with the builder. If the stick straightens when the load is off, or if this is somehow a learned bend, it's tuning. The other tuning possibility is that, um, you're doing a horrible job. Try starting from the bottom and working up, taking up a little at a time on each turnbuckle, and checking frequently to see that the mast is staying straight.
Some woods bend easier than others.
Let me know how it comes out.