Half Relationship!?

Has anyone ever seen a relation ship existing in the child table settings, but not existing in the parent table settings?

I have heard of orphan records, but I imagined that if a relationship was deleted that it would not exist in either the child or parent settings.

I found this when I noticed the related record fields was blank in the child table. I looked at the table-to-table relationships settings and the relationship is shown. I open the parent table-to-table relationships settings and the relationship is not shown.