with subpixel antialiasing enabled, I sometimes get weird aliasing problems. I've noticed that these issues tend to appear more often when the option to highlight the current line is enabled. Anyway, I took a couple of screenshots of the problem:
In the first one if you zoom enough, you'll notice that the word "highlight" is wrapped within a thin white line. The second one, shows that aliasing problem only when the caret is positioned on the same line.
OSX, v2 b 2111