Hey @Alec,
Just checked with the team here. As @RobLauer mentioned, setting sync: true on a note.add request only guarantees a sync of that individual file.
In most conditions syncing one note will also sync all other queued notes, but it’s not guaranteed. For example the Notecard could temporarily lose connection to Notehub.
I’m guessing that’s why your notes almost always sync at the same time, but occasionally have a bit of a time difference. I’d try hub.sync and see if that fixes the discrepancy.
Thanks,
TJ