So if you look really closely at the following questions, there are a couple of minor differences between the 1st & 4th compared to 2nd & 3rd.
The aliasing looks different but that is only because the 1st & 4th title appear to use #3d3d3d while the middle two use #666666 so it plays tricks with your eyes. But why the different colors? I thought I was just getting tired but I took the screen shot and analyzed the colors with Photoshop to prove that it isn't just me.
This is a really minor nit, and I don't expect anyone to spend any real time on this - it is more to document my observation (and see if anyone else shares my observations) than any request for action. I viewed the source and all four headlines are marked up with the same tags pointing to the same styles, so I have to assume this is browser-dependent (as I see the issue in Chrome 20.0.1132.47 and not in Firefox). I do not have any user-styles, scripts or any plugins other than AdBlock. This persists through a page refresh and even a reboot.
Anyone else see this? I should I delete the question, pretend it doesn't bother me even a little, and never mention it again? :-)