Leaderboard with and without "Ads By Google"

Why some ads are tagged while some others are not.

[AlexPAlex]

I run Leaderboard ads in many pages with "Image" only option since last week. In some pages, the ads are shown with small link "Feedback-Ads By Google" below the banner while in some pages there is no such link, but just the banner. Why is it so, any idea?

[thewebboy]

Is the ad animated? if so I think the tag is removed.

[AlexPAlex]

Yes, the ones without tags are animating.