It definately sounds like a spine issue,but I dont think it is.My program is showing you dead on with your setup.Unless you are drawing longer than what you think.Do you know your speed and I could tell you for sure if spine is an issue.
It might be a torque issue.You might have to address your grip.

I don't know for sure but just making observations.
This is exactly the type of problems that occur when you compromise centershot for good paper.
Don't bandaid by moving the rest,fix it.