The only part that is relevant to you is the last part:

"In some cases, third parties can add malicious code to legitimate sites, which would cause us to show the warning message."

So maybe you sourced some external javascript or advertising that contained something bad.

Edit: what does that obfuscated code at the top of the html do? http://pastebin.com/u3T3wJcG

Edit2: I think it's a bit irresponsible to post a page that has been marked as containing malware to a highly trafficked website. You could have at least run it through some alternative scanners first.