2013-P MT Rushmore New Mint Error?

It's Die Deterioration. The doubling is towards the rim. It looks different because the letters are incuse. Coop has some great photos that show Die Deterioration Doubling with a detailed explanation of what's happening. Let's see if he checks this post.

Are you there, Coop?

Looks like a die chip if it is not supposed to be there. Note on the 'RUSH' area above it? Note the die flow lines on the die. That is die wear starting to show on this die. So the die wear/DDD ( Die Deterioration is just starting on this die. These flow lines start to appear when the die is reaching the LDS (Late-Die-State). Now the obverse devices are looking thinner, so that die has been polished because the die flow lines are not showing when your coin was struck. Note on the inner part of the rim, you can see the metal striations on the die on that rim area. So why did they not polish the reverse when the obverse was polished. Keep in mind the letters on the outer ring of the ATB Quarter devices are incuse. So they are raised on the die. Die polishing would affect them when a polishing happens. So they have opted to not polish this die yet because of this weakening of the incuse devices.

It's not suppose to be there so is it a die chip ?=die break?