If you have a list of items, and clicking on an item takes you to another detail screen, and then you click on the 'back' button on that screen, you automatically jump back to the top of the list instead of being on the item you had clicked.
Maintaining the scroll position is very important for those apps which have numerous items, and scrolling down every time after clicking on a detail page seems like a bug that could probably be addressed easily, and should be.