According to this calculator:
62 is not the diameter. According to that site, the Radius of the sphere that the Dome is the Cap of is 35.69444.

The panel base width is pi*ArcD/36 = 5.41

The height of a (circle) arc 5.41W with Radius 31 is 0.11794
That is the approximate difference in radii of a R:=31 circle touching the center of a panel and a circle touching the edges of that panel. A difference of ~ .38%.

The difference in the lengths of arcs one panel wide of those Radii is 2*pi*.11794 or 0.741%. The difference in the widths of a flat panel and a radiused one is in the ballpark of half that because that difference is a sine function.

Now we can use this calculator to compare the areas of a dome 62 wide and one 62.11794 wide

R:=31: A = 7056.0171
R:=31.05897: A = 7078.6326
Average = 7067.32485

Approximate error factor of flat vs arced panels = +- 0.1597%