Alarm doesnt work when smsed iPhone

So here is an odd one. Im currently doing supps and therefore waking up at about 5am so I can get in a couple of hours study time in before work. However this morning I didnt get awakened by my 4:40am, 5am or 5 plus alarms that I set up on my phone.
When I do eventually wake up at 6:30 I have that little message preview thing that you get when someone SMSs you. The moment I unlock my phone all 5 of my alarms ,that should have gone off already , decide to go off.
I have a pass code set on my phone and Im running 2.1. Has this happened to anyone else or is it just a fluke?
iPhone 3G Other OS