1880 Morgan- Die Gouge Or Post Mint Damage?

Undoubtedly post-mint, probably not in the bag. Note that the marks near the date are relatively smooth, and extend from the field onto the 8. A bagmark would extend this way, but it would be rougher/more irregular. The displacement of metal into the bottom of the E is the clearest indication that LIBERTY is post-mint, also - since that area is raised on the die, it's highly unlikely that it would happen like that during the minting process.

Remember, silver is a relatively soft metal. It wouldn't take a whole lot of force to create such marks on a silver dollar. You can create a sizable rim ding on a Morgan just by dropping it from waist height onto a hard surface.

Definitely post mint damage. If the die were gouged the effected area would be raised on the coin not indented. As SuperDave has said, the mark also extends into the 8 which also indicates post mint.