are you JB? do you use biteSMS? also did you check your calendar to see if you have events my text tones are custom so I can't remember but don't the calendar events and text tone sound similar? just throwing it out there. I had the same thing happen but it's because I use biteSMS so although my phone went off I guess I ignored it too long but the message was there just wasn't showing on the screen. I forgot to add if not try a reboot to settle the phone down, you just performed brain surgery maybe it's a bit shook up.
