Venison Sausage Bad or Smoke Ring?

First time doing cured venison Summer Sausage, smoked 6 tubes NYE, and I pulled one out and it has this ring? Is it spoiled or is it a smoke ring? Pulled at 160* internal and threw in a cooler outside overnight (25*F) then sealed and stuck in the fridge

First time doing cured venison Summer Sausage, smoked 6 tubes NYE, and I pulled one out and it has this ring? Is it spoiled or is it a smoke ring? Pulled at 160* internal and threw in a cooler outside overnight (25*F) then sealed and stuck in the fridge