I have a similar problem. Try contacting your network provider as the iPhone may load the time info from the internet or GPS. I have a similar problem. I was listening to the radio and there was a time announcement. It was a coincidence that I've checked my phone, and noticed, that either the radio was delayed (I highly doubt it as the FM waves are travelling, let's say instantly) or my iPhone was five minutes forward. Apple support operator walked me through a few steps, that worked, maybe, I am not really sure. Change the calendar to buddhist and restart your phone, then change it back to Gregorian and restart it again. You may want to get a mechanic alarm clock (no electronics at all) to be a 100% sure.