From a chipped die. The hollow of the P is raised on the die. As the die is used, it weakens and wears. A very weak point is that raised portion of the P and it sometimes breaks away from the die causing the effect you see on your coin.
Die Chip,the little stub Broke Off/Over Polished on Die that makes the hole in the middle of the Mint Mark. Happen a bunch on many many Die's over the years.