Have the shop put them on an arrow spinner and show you they are bent. You will see it when they spin pretty easily if they are bent.
By the way, any arrow can bend or warp, even carbons irregardless of the hype you hear about them. They are not either straight or broken, one of the biggest myths in archery right now.
ACC's are great arrows, but you can ruin them, and I would suppose they could go over time if you shot them enough. Especially for 3-D, a 3-D target is pretty abusive to arrows compared to a bag target.
If you couldn't ruin them they wouldn't be making a million of them a day
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Paul