It did finish at exactly (well, insofar as the hydrometer is concerned) 1.021 - the higher mash temp allows for this - more unfermentable (maltotriose/traose) sugars.
As for beersmith, my guess is that's a 5gallon batch for the OG - no idea where that FG comes from though, that would be 85% attenuation, which is pretty optimistic for most yeasts.