Top Of Collumn?

My Guess is Machine Doubling

It's not Machine Doubling. That's a flat, shelf like -scooting- effect of the design. The Machine Doubling has to be a part of a device. This raised area is not supposed to be there...rules out Machine Doubling completely.

What this is matches closer to what TreasHunt said. It's a retained die chip - a broken piece of the die that's still attached to the die.

Retained pieces can be either raised or incuse on the coin. Don't ask exactly how this happens, I don't know...but it does. I've seen a number of cracked skull Lincolns where the matrix of die cracks cuts out a piece that actually sinks in the die and causes that area of the coin to be raised higher than normal. Additionally, although with slightly different dynamics at play, Retained Cuds are almost always raised on the coin.

Ermm....a Retained Cud would be at the edge of the design, because the definition of a Cud is a die break at the edge of the die where a piece of the die falls completely off.

This is a retained die chip. A piece chips out of a weak spot in the deisgn and falls out, but the integrity of the die remains. That's the biggest difference between a die chip and a Cud. Chipped dies can happily punch out thousands of coins after the chip, but a Cud is a die about to break apart.