I don't think they are pre-seasoned. They come coated in some sort of wax/oil that takes a bit of effort to scrub off. The Cooks Illustrated instructions seemed like overkill, but in hindsight it might have a been a good idea to follow them. I seasoned it with neutral oil last night before cooking bacon this morning. After the bacon and eggs, I washed it out well and hit it with another layer of seasoning. My cast iron is pretty slick so I think I should be able to get this one there the same way.
Now I am wondering if I still "need" to find a Griswold #43 as it seems to be very similar to the Darto No. 23. Oddly, I think my mother's #43 is lighter than my new Darto. I may have to compare.