Neck pain and weakness after chiropractic adjustment, should i be concerned?

Depends on whether : It was there to begin with ;severity as well if any radiation into limbs as well if associated with any other neurologic issues like numbness.If symptoms are troublesome ; persisting/worsening, see physician for evaluation. If resolves, inform chiropractor as to what occurred to avoid any future issues. You may have a spinal instability or spinal stenosis or a large disc herniation or combo.