Apologies for arriving late to this party, Shane, but what you were experiencing is a lingering InDesign bug. It happens only occasionally so I’ve never been able to determine the cause other than it is related to child Masters (i.e. using the Based On feature) where objects in the parent Master bleed off the left trim on the left-hand page. In your case, the spine-touching instance might be triggering the same.

I have fixed it in the past by doing the following (a ‘turn it off and back on again’ method):
– open Master Options for the child Master, change its Based On setting from its parent Master to None, click OK.
– re-open Master Options for the child Master, change its Based On setting from None back to the parent Master, click OK.
– That’s it.

Sorry if this is not relevant to your case. Good luck.

Alistair