Password replication issues?

Ok, maybe I'm just batty. I recently upgraded our OD system (part of Magic Triangle) from 10.4.11 to 10.5.6. That's one ODM and 3 replicas. I will start with - I don't know if this ever worked - but if an OD admin logs into their localized replica with WGM (instead of the ODM) and changes their password, that change won't replicate back to the master. However, if they log into the master and change their password, it replicates down to the locals. Is this normal behavior? Or should I be looking for something that is broken?