Reference data still resides in the database after deleting the node

Description:
The node reference data continues to live in the database after the node that was being reference has been deleted.

Recreate:
- Setup a content-type (example) with a node reference field (widget: radio/check boxes).
- Create a new node from that content-type (example), then make a reference to another node using the node reference field. Save.
- Delete the node you made a reference too.
- Look at this table (field_data_field_YOUR_FIELD_NAME) and (field_revision_field_YOUR_FIELD_NAME) the node reference still exists. If you look at the node table, the nid thats still being referenced shouldn't exist, since it got deleted.

I'm willing to help out with a patch, I was thinking you could use hook_node_submit(). Any suggestions?

Thanks!