Good call, there was a squished spot on the belt!
One of the pulleys was loose as well. 
I had used locktight on the pulley’s set screws, But it still managed to work loose somehow. 
I flipped the bet around so the damaged area was on the far end, outside of the range of this carve. Then re-set the pulley and did a new carve.
Much Better!
A good carve and the raster cut didn’t produce some of the odd wavy surface effect the spiral carve does.
I will have to keep closer tabs on the Pulleys. I really need to replace the stock set screws with a longer Allen screw. They have a bigger hex head so I can torque down on them better.
Or upgrade to the gear reduced motors. Because the motors are higher torque they use larger set screws with a key bar to lock the pulley in place.
I am happy that I was able to spot, identify, trouble shoot and fix the problem so quickly
I think I am finally starting to get the hang of this. 
Moving forward, I am going to change the raster direction of the rough cut to be in the X axis direction. I have always ran it in Y. I am not sure why, probably because that is the default? But I suspect the rough cuts are putting a lot more load on the axis, So minimizing the load on the Y may help prevent things from getting out of alignment in the future.
Also, for the reclaimed pine, I am going to try reducing the machine allowance on the rough cut to see if it will make less fuzzes. I might have to add a second rough operation with the smaller bit.