Hi all, I've got an iPhone 4, and ever since the iOS 4.3 upgrade I've been getting some weird behaviour. Once a day, the phone will make a notification sound (or vibrate), without any message displaying on the screen. Up until the iOS 4.3.1 upgrade, I noticed that this happened once a day without fail, at about the same time each day (16:47, then gradually advancing over about a week to 16:49). I haven't really been keeping tabs on it after the 4.3.1 upgrade, but it made another random vibrate just now, so I'm assuming the issue isn't resolved. Any ideas what might be causing this? Cheers.