<p>brassmonkey makes a good point - it could have been a bubbling error. I wouldn’t bother canceling if you feel you achieved the good CR score you were hoping for. If any colleges DO ask for an explanation, you could tell them you weren’t feeling well that day, and while you were able to concentrate on the more important CR sections, you couldn’t maintain the same level of concentration for the other sections that you’d already done well on in the past.</p>