FCD was less than calc MPG. Hmmmm...

OK guys and gals, here is what's happened. When I bought the car it had the usual complimentary full tank of gas. The odometer read 37 miles and as best I can remember the FCD read 34MPG. I figured that was about right for 4-5 mile test drives that included 1.5 miles getting on and off the freeway.
Yesterday I filled up for the first time. The odometer read 466, it took 7.468 gal, and the A tripometer read 56.6MPG @ 465 miles. My B tripometer read 63.3 at 361 miles (from this thread).
Well, as you can see, the calculated mileage, at 62.4MPG, seemed way high. So I figured I just hadn't gotten it filled all the way, even though I filled it until it clicked off the second time. So today I stopped to add more fuel on the way home from work. I added .666 gal, again with 2 clicks of the pump, with an additional 35.3 miles on the odometer. That calculates to 53MPG (the FCD read 65.3).
Now I rather expect a discrepancy on the mini fill up today, but even when combining the 2, I come up with 61.63 calculated MPG.
That's a full 5 MPG over the 56.6 FCD MPG.
I must be screwing up somewhere. Everyone else is reporting calculated mileage lower than the FCD displayed mileage.
Comments welcome.......