Remember that you should be flying the airplane for pleasure. If your fuel
gauge shows empty it is not fun to fly. Like the others have said it is
possible a fuel leak changed your calculations.

I wonder how many pilots on this newsgroup have run their airplane to where
they used ALL the useable fuel. Try it, it is NOT fun. I had it happen in
Mexico where fuel is not always available. I would rock the wings to check
movement in the fuel gauges. The last check I did minutes before landing
showed NO movement, dead. Luckily I landed, of course making a high approach
in case the engine quit. When I fueled the total gallons added was exactly
the useable amount of fuel. Never do that again....and never went back to
Mexico.