[cairo] Horizontal artifacts rendering to an image surface

[Floyd May]

I've got a scenario where I'm getting artifacts like the following
image:

http://imagebin.org/222338

Notice the three horizontal lines near the top. In this particular case,
clipping is not involved.

This is in a larger app, and I can't readily post source code at the
moment.  I'm currently working on boiling this down to an
easily-reproduced case; however, I wanted to fire a flare first and see
if this is a known issue. Am I doing something wrong? Could this be a
bug? Can anyone suggest a workaround?

This is using version 1.10.2, based off a recent download of the GTK+
Windows binaries.

Thanks,
Floyd