I have no idea what an "over punch" is. Can you be more specific in what you see different about this coin?
The coin can't really "bulge" because it is confined to the space between the dies, which in general does not allow for the coin to warp as you suggest. From the pics provided, my guess would be progressive indirect design transfer. http://error-ref.com/progressive-indirect-design-transfer-.html
Thanks for that one the only thing a little confusing about the pidt is it is stated from obverse to reverse bulging. But it does look like pidt.
I see what you are talking about David and there is no documented error of that kind. It is most likely PMD. Although non_cents might be right with his answer I would guess that it may be a heat bubble. I had a dime that was very similar although it was a lot more severe. From what I understand it is caused by heat to the coin. Hope that helps.
Since the dies are slightly convex, the strongest force felt on the planchet is in the center of that planchet. However, in the case of the Lincoln cent, the center of the obverse die is incuse, so the area on the obverse die that experiences the first and strongest force is