Welcome to the AC forum, Ben.
Have you ever heard the expression, "it's not a bug; it's a feature"? I think that applies here. One of the priorities of AC (or any EMR, for that matter) is to be certain that you have seen any important item that is placed in a patient's chart. It is easy to imagine the negative consequences of an abnormal lab or radiology result that is filed without you seeing it. So in general, any item that is imported by a non-provider will generate the type of message you are seeing. If the item is later signed-off by someone else, your message is still there, and you must delete it.
If your NP is also a provider (and is listed that way in AC) then when an item is imported, the staff doing the import has the option of choosing who will do the sign-off. If they know the NP is seeing the patient, they could choose her and the note will be generated in her message box.
Other choices: you can make it so that NO sign-off is required on a document, but that runs the risk of NO ONE seeing it.
Let us know if you have other questions about this; others here may see it differently.