Node created date being changed on node save.

I can't seem to find anyone else who has had this problem, nor can I find documentation to say it is expected behavior (perhaps I need to look more but in the meantime I thought I would write a quick forum question while I plow through code).

We are finding that the node.created date is being changed when a user (who is not an admin, and not the original creator) edits that node. I would expect that the created date would never change unless specifically changed in the form field.
This is not a good thing, as we have views sorted by the created date. Is there a business logic in Drupal that requires an UPDATE of the node.created field based on a) a change of role b) a change of user ?

Any thoughts, or insight would be appreciated.

Thanks !