R105p4 This proof appears to be from the bottom row and clearly is a short transfer. The question is: Is this a printing variety or can a confirming copy of a stamp from this position be found with the same short transfer making it a plate variety?
A short transfer is by definition a plate variety, and would therefore be repeated every time that plate was used. I do not believe that this is a short transfer. It seems most likely that the proof had something stuck to it which removed some ink. It seems highly unlikely that the proof was under inked, Joseph Carpenter was usually very careful in producing proofs since they were usually seen by important people and they would be the finest examples of his work.