Mine started doing this about 5 fills ago. I was worried when it happened -
aaaaack, just filled with gas and it still says empty! And there are lights flashing too! aaaaaack!
Then I checked the clinic and found it was no big deal - just a sender unit issue. After I put about 20 or so miles on the tank, it works normally again. I'll keep it on my radar to fix at some point but won't be getting (any more) gray hairs over it.
This place is awesome - and keeps me looking younger too...