Pearl Drums,
Sorry to hear of your problems but I believe its a possibility with any bamboo shaft as it fully seasons or expands/contracts with changes in weather and season. I have bought 400 bamboo shafts over the last few years, all from the same source in China. All are seasoned, straightened, ground at the nodes & lacquered. Did not notice any problems with the first 300, then with the next hundred I had approximately 18 split down their length within a month of arrival. Contacted the supplier, Tiger for those who know him, who asked experts etc about the problem and could only suggest it was due to the difference in temperature and humidity between where the shafts were produced in China where it was the height, or is it depth, of winter, and my home in Australia during the height of out summer. Tiger refunded the costs of the damaged shafts and suggested I only buy when the relative climates were closer together.
Since then I have occasionally noticed split shafts when going to make another arrow, similarly I have discovered split arrows that were completed the previous season.The later split shafts and some of the split arrows did not come from the last batch, but came from the first 3 batches so it was not a problem with the one batch. I know this because the batches were of different spine and the later splits have been spread across the spines.
So I suggest its a quirk of the material, and is something you will have to put up with if you use bamboo or any natural material. Would you be doubting your material if you found a longitudinal split in a wooden arrow?
Craig.