Better pics are needed, but it looks interesting. It appears to start at the rim and go in, but I can't see if it goes back to the rim elsewhere.
sometimes it's hard to tell what is wrong with a coin just by looking at photos. It looks like your coin may have been struck thru some thin foreign object like say maybe a piece of planchet scrap.
I would almost call it a Post strike Damage, perhaps it was even an in circulation strike! Very narrow oval for anything I can imagine! It could have been a clip from a previous mis-strike but it does not have a large enough arch in the dent to be a large coin piece, as best I can tell from here.
