Hey @itdidnotcomehome , it nearly came home , next year we will bring it home ⚽
You have it right, the effect you are seeing is the subsurface modifier smoothing the corner making it look rounded.
In the example shot from the lesson, Kent actually had duplicated verts some how, which is why it looks different. Just after this Kent fixes the problem and continues to have geometry just like yours.
You may have extruded a little further but yours looks good. 👍
