The post time background is cut off by the One Box content when posting questions/answers and maybe more.
You can see the cut off in the top right corner. It's supposed to look like this:
If I recall correctly, we didn't fix this back in the days because every possible fix we could find caused some issues in IE7, and the current handling was "good enough". But since we're past the "caring a lot about IE7" stage, I've made that change now (it'll go out shortly with the next chat build).