Apple recently changed their purchase policy in order to avoid any accidental purchases for applications on an iPhone, iPad or iPod Touch. This change is to protect users particularly childrens from making unwanted app purchase or in-app purchase.
Apple’s software update iOS 4.3 asks users to re-enter the password every time when there is a tap on the app purchase. Previous system was once the user entered the username and password that can exist up to the next 15 minutes so that another accidental purchase can cause additional charges. These are the situations probably when children’s having the device and accidentally taping on the in-app purchase for the apps like Smurfs’ Village and Tap Zoo.