33% across 3.5m is not at all impressive, and I don't know why they even bothered mentioning the 17% grades.  I would think that a cut-off of 30% should be a bare minimum.

However, one cannot discount the possibility that a lot more will be found. 

Also, an analogy that may not be that useful or appopriate, but which speaks to the thickness of the intercepts:  A sheet of paper by itself may not weigh much.  However, a sheet of paper that is ten miles square weighs a lot.  Especially if that sheet of paper gets a lot thicker when you move a few meters sideways.