This is a screenshot of the Mashable iPhone app.
When you open up an article and scroll down as you read it, the back button on top left gets hidden. When you want to get back, you have to tab somewhere on the screen, and with some irregular delay, the back button comes back.
Here, designer should have known that the Back button should be the primary target and make the target area larger than the email link just below it. (If possible, should have considered not having any other interaction near the primary target.)
Try it out.