Thank you for reporting the problem.
Have you entered fill-up on 02/16/2010 before entering one for 02/10/2010? Did you have to modify fill-up details like date of the fill-up after you added it?
Our site is fill-up date-sensitive as people sometimes forget to write down mileage on the receipt but we can still calculate average MPG for 2 or more fill-ups in this case.
I've just updated both your fill-ups in question starting from earlier one and MPG values came back correctly.
Please let us know if you see the problem again.
Thanks and have a great day!