Rotor/Reluctor Phasing Question

While attempting to check the reluctor to pickup clearance in my son's '68 Dart 318, we found the following anomaly. With the balancer set to 18 deg BTDC (our idle timing setting), we found that the reluctor was not aligned with the pickup. Since the car runs fine, we're a little confused. Shouldn't the reluctor be aligned with the distributor pickup at the idle timing setting? The photo shows the alignment at 18 degrees BTDC. The balancer markings have been verified with a piston stop, so I know the balancer is correct. Also, the vacuum advance is not hooked up.

Anyone have any thoughts on this...???