Look at the size of the motto devices? They all look smaller than normal. So the die was obviously polished. So something may have been dropped on the die leaving a slight indent there. Showing on the coin as a raised area. It is were a doubled die, more than one device would have been affected in the same direction. That spread would have been larger than the 1955 big
DDO. Just a contact mark on the die. (Or something on the coin?)