Very frequently when I receive a call and then swipe the screen to answer it jumps back to the left. I try repeatedly and eventually the call goes to voicemail. Both my wife and I have iPhone 4's which we got on opening day and hers does this also. Wondering if others have experienced this? Is is software related or a hardware problem. With the 1 year warranty coming up soon I'm thinking I should go back to the store soon if it may be a hardware issue. We are running the latest OS and have had this problem previously using several other versions of IOS 4.x