Its a die chip. The die is crumbling in this area and the more coins it strikes it just gets worse. It happens.
fun error Could be a piece of another penny that got stuck on it. Or also it could be zinc rot. A die crack is a good possibility. Hard to really tell from the picture. Perhaps a close-up, and an angled shot to be able to see edges/shadows would help.
I both 2007-P & 2008-P like that.2007-P about a 1/2 roll & 2008-P one at the end of a unopened roll you would think Philly would try to fix that.
I guess we are the only ones who notice. The die is probably still in tollerence with the mint's standards. Seems like they don't get too excited till the dies split in two and they still have a few more slip through before they are pulled. LOL