Thank you everyone! Just got back from the boat, and I was looking at it all wrong.
I was standing to the side of the mast looking up, the last 5 foot of the mast is tapered to the back. It was a optical illusion.
The indented ridge follows the taper, the back of the mast is straight.
Unusual to have taper on masthead rig, but I have seen it before. Maybe something like this one:
Anyway, that should ease your concerns