Hey Buzz, this tree appears to have prominent branch bark ridges and I am thinking this might also be one on the limb you are questioning. As UF said, hard to say for sure from the angle, but I wouldn't be too concerned with it unless a closer inspection shows differently.
The limb is arguing for supremacy, but IMHO would create too large of a whole in the canopy to remove entirely. Again, this is stated without being able to walk all around the tree. It's not perfect, but not something I would consider a large defect .
Ok, the mirrors on the tree to deflect deer is a new one for me. The purpose was to keep bucks from rubbing, which damages the tree...and the previous homeowner didn't think attaching mirrors to the tree a problem? Well, I'm adding that one to the anecdote compendium.
Sylvia