The PCA's BCO, in Chapter 21-5, there is this vow to be asked of TE candidates:
Do you sincerely receive and adopt the Confession of Faith and the Catechisms of this Church, as containing the system of doctrine taught in the Holy Scriptures; and do you further promise that if at any time you find yourself out of accord with any of the fundamentals of this system of doctrine, you will on your own initiative, make known to your Presbytery the change which has taken place in your views since the assumption of this ordination vow?
How often does someone deem themselves to be "out of accord", resulting in their voluntarily taking themselves by the scruff of their necks and hauling themselves before their Presbytery? Has it ever happened?

I can imagine it happening if a TE becomes an RC, or switches over to credobaptist, as those are pretty cut-and-dried differences, but I'd think more subtle doctrinal shifts would slide under their own radar, so they would sincerely believe they're in accord when in reality, they're not any longer.

Anyone know if there's precedent?