I think that if I was a "regular" customer, they'd exchange it no questions asked.
I also had an AG brush that became useless once the entire pad popped out. I was able to exchange it at a store, no questions asked, and was told that this is a common problem. Since it's a common problem, that lowers my grade on this item to a D-, because it it's a known problem and the company doesn't address it with better manufacturing, that smells of Fail to me. I do happen to like the 'feel' of the brush in my hand, which keeps it from a total F grade.