While I'm at it, how strong is the bow you are wanting to make?
I would call that furrow a flaw(ever so small though), rather than a violation. You could probably get by without doing anything else to it. Even though the sapwood is unbroken, that localised furrow might cause a hinge on the belly, hard to know until you try it.
Personally I would rather be safe than sorry, and leave a small swelling in the sapwood, out at the edge, or take the entire sapwood down to an even level as Del does at times. Virtually all the old yew bows had their sapwood shaved and levelled off, decrowned into a flat back.