Did you drive it down to empty when it happened, I've seen this usually on older cars where the arm gets stuck on the bottom. solution is usually to have only around 1/4 tank, find an empty parking lost and get some g's to either side to get it loose. Otherwise just go to the dealer as it could be the sensor, Sending unit or just the gauge motor. all a PITA to fix yourself, Just take it to the dealer as close to empty as you can, if he has to drain your tank, you will probably loose whatever you have in there, (which will probably end up as a free gas for the mechanic who is working on it)
I don't usually get too low. I had a problem with it a couple of weeks ago. But then it was fine and I went on vacation and left my car behind. It's back though.
Now, this should be covered on the warranty I imagine? I'm at like half a tank at the moment (I estimate).
I had to hit the brakes pretty hard a few weeks ago. I wasn't driving too fast or anything, just traffic happened and person in front of me hit the brakes quick too. I didn't have any problems then though or for at least a few days.