Illustrator Rigged/Extra outlining

From time to time I see rendering glitches on objects like the example you posted. Sometimes it depends on the zoom levels. Most often I see the rendering issues while I am adjusting direction handles on an anchor point. I’ll be bending a curve and see the glitch happen in real time. Adding enough anchor points along a curve, or making the curve mild enough or symmetrical enough will reduce or eliminate the issue.

This issue looks like a good illustration of why the type industry shifted more towards using TrueType outlines with quadratic splines. Fonts with Postscript outlines could use fewer anchor points and be more efficient (if not more graceful), but the cubic splines are more difficult to render on screen. TrueType outlines render faster.