Menu -> File -> Utilities -> Customer Defaults...
Use the Search Function (binoculars icon) up un the right corner of the Customer Defaults menu that pops up
Search for "Create With Centerline"
Should have figured the terminology would change, so that my endless searches, and searching would fail. *EDIT* I swear it was called "automatic centerlines" in the past, but looking at NX9 native, it simply says "centerlines".
I suppose I have to go thru all of my drafting formats now too, since the setting terminology has changed, to turn it back of in them?