I'd lean towards struck through debris (wire brush bristle) but don't think the light would reflex off coin differently from the north or south sides of the mark as if metal was pushed instead of stamped. Is that a reeded coin? or Would reeded coins be included in the bag?...
I'm not saying it is a bag mark. I'm saying it might be a bag mark. Coins are shipped (or were) to banks or coin wrapping companies from the mint in canvas bags. The coins hits each other inside the bag, when the bags are thrown around during transport..... Hence bag marks.
rosecoins could you post a image of the obverse of your coin. I would like to see. if there is a certain mark on the queen side of your coin. then I will tell you what this mark is from. so you will know. there is another member here on the forum. that has the same mark on a coin as you do. I also have a coin with the same mark. my coin is a toonie sir john a macdonald. I will explain later once I see your other image thank you