I just saved the source locally and tested it out. It seems that when the styles do not appear, the LINK element is resolving as:
<link rel="stylesheet" type="text/css" media="screen" href="http://cdn3.infoq.com/styles/style.css;jsessionid=2BAD2D184D56C3163ADC70B99E711F47" />
..the important part being the ';jsessionid....' which is knocking the css out of commission.
On a reload, that jsessionid apparently kicks into action for some reason, and the LINK element resolves normally as:
<link rel="stylesheet" type="text/css" media="screen" href="http://cdn4.infoq.com/styles/style.css" />
I'm not sure what is actually causing the jsessionid to not work, then work on reload...but that seems to be the culprit in one way or another. Also, I had the same exact experience in IE7 and Safari...so definitely not a browser specific thing.