Google limiting number of ads per page?

Anyone seen anything like this?

[ari11210]

I have a page on my site that is related to a low paying keyword. I had been getting 3 ad units full of ads for this page for a while, but the price per click wasnt vey high. Then, about a month ago, I tweaked the page a bit, and am now receiving ads for a much higher paying keyword (over a dollar/click) - but only in the first ad unit, the other 2 are always empty. The ads are for a very popular keyword which I know there are many ads for. I am wondering if google is capping/limiting the number of ads per page since it is a high paying keyword, as since the ads have changed to these new ads, I have never seen more than one ad unit populated.
Has anyone ever seen anything like this?
Does anyone have any ideas for me to get the other 2 units to be populated?

Thanks in advance,
Art

[ari11210]

Anyone ever see this?

Thanks

[hyperkik]

It is impossible for anybody here to answer that question without engaging in speculation - your guess is as good as anybody else's. But others have reported experiences consistent with your thesis.

[Jenstar]

Could be more advertisers have opted out of content, particularly for more expensive campaigns.