This reverse die chip is not a genuine die dot. The term die dot generally refers to a round mark in the die caused perhaps by the engraver’s awl. The only proven instance of a genuine die dot is the 1875 DOT-001.
Other similar die chips near the center of the reverse are the 1864 No-L CUD-004, ODD-004 and the 1883 ODD-001. Can you find another?!