+1 to Hardmill, check for holes/gaps. Also, hang your left pinky over one key to the left and push it down once. (caps lock)
:edit:
One other thing; turn on the toolpath display and z00m in on the area. See if you can see the deviation from the 'normal' toolpath. If so, it's a software setting/issue, if not, it's the machine or the post. Couple of options if it's the software; fix surface holes/gaps, tighten tolerances, manual edit to the toolpath prior to post, or after if unable to do it before. Food for thought.
HTH
:/edit:
'Rekd teh (in the voice of Eric Cartman); "Screw you guys.. I'm goin',
home !