A "new record" script can set a value in a field to identify it as created by that script.
A field can be set to auto-enter data when the record is created. If you do not allow "auto-entry options" during import, that field will be empty if the record was created by an import.
Alternatively, you can script your import and the script can use Replace Field contents to update a field in all of the newly imported records to "mark" them as created via import records.
I actually just thought of that just before checking back here.
What I ended up doing is creating a couple of more buttons that set the field with other parameters to reflect changes requested by phone call or email requests, plus an import button that replaces the field contents with Imported.
All of this is used in conjunction with NightWings Ultralog custom function to track how and where changes were requested and timestamped..