Ronnie:
The warning is because your browser asks Google to check the security of all pages that you try to access. Google has detected that AB takes content from bit.ly (which, knowingly or otherwise, hosts some malicious content). Since AB's techies have spent the past few days trying to sort out such problems, that information may well be out of date anyway.
Don't worry about it (but avoid clicking on any ads here, which is where any dodgy stuff might be hiding); AB will get the site 'white listed' again soon.