I have an iPhone 4 that I've had since launch day. For the past month or so, the home button fails to close apps, sometimes not working at all. Imagine, for example, not being able to close out of Mail for 2-3 minutes after opening the app. The button doesn't "feel" to have a physical problem. I've restored the software, to no avail. Unfortunately, the phone isn't covered by Apple Care. I have an appointment this evening with a Genius. Any thoughts on what my options will be at the store?