OK....you are POSITIVE both batches are doing this? I would almost say the ones you got from Ebay may have been defective to begin with so the guy sold them anyway. Sad, but it happens. If you are 100% positive it's both batches, it's definetly something you are doing. I've been shooting those for a long time, as have guys at the shop and I've NEVER seen that before, well, not without an outside force such as another arrow.