Ah yes, I see what you mean, it must be an editing error. One moment the edges are not there and the next moment they are there.

You can see also on the inside that there is even more work done in there. I think for now you can use the knife tool with K and make a few cuts so you can assemble the shape you see.
You can maybe achieve the same shape by selecting those 3 edges:

and beveling them:
