I second that opinion. Adding such a question would prevent us from spending our CC by mistake or misclicks. I recognize it would probably cut your profit slightly, but you do have quite good relations with the community, and adding this question would improve it even more; that, in turn, would probably translate to much better profits in the future.
As it is, I'm sometimes even afraid of clicking a button if I see it's purple, for fear that I can get charged CC right away.