Thanks for the thought. I hadn't thought about the moisture content aspect. However, I think this SHOULD be minimized by the way each of the 6 strips are cut and glued up.
Now that I think about it I might very well have caused the bow myself. The technique, in a nut shell, is to mount the straight blank on a lathe and using a set of sanding blocks sand the taper. Well, the taper is getting quite small toward the tip so I may have caused the bow by biulding up heat from the sanding process.