Springfield, VA is pretty urban, and might not meet with Tesla's objectives. Woodbridge, VA (near Potomac Mills Mall) might be more in line with what they typically do for locations.
It is, however, outside the DC metropolitan limits, at the junction of major corridors, and approximately 80-90 miles from the supercharger outside Richmond, and about 110 miles from the supercharger in Delaware.... around the halfway point.
Moving it farther South to Woodbridge, would make it only about 60-70 miles or so from Richmond SC.. and subsequently farther from DE. that would seem odd positioning. It would also remove it from being easily accessible to people travelling the I-495 beltway to/from 66 or 50 going East/West or branching up 395 in to DC.