It looks like it was struck with a heavily polished reverse die. The die may have been reworked to remove damage from a clash or something similar and then put back into service after the damage was polished away. This can result in a loss of detail on the high points of the die (low points of the coin). I can't tell from the pics, but if you look closely, you may be able to see remnants of a clash or die damage This is also what causes the "floating roof" Lincoln Memorial cents