You could try the warranty, and Klipsch may replace them, but they wouldn't have to. It's not Klipsches fault there is a dent in the woofer. If you had bought them brand new, and they came out of the box like that, then it would be their problem. But whether the box was sitting on the floor in a store or in your home, a dent caused by someone (in other words abuse) shouldn't have to be covered by their warranty. The store should have to cover that, unless they stated in the sale, as is - no warranty from the store.
A warranty is for a defective product that goes out on its own, not for a product that is broken by abuse. How would Klipsch know you bought these open box or not? I don't know, so maybe you will be ok - I can't imagine a single woofer costing them that much, and they would probably rather make a customer happy for the small price.