Google offers automated and often repetitive messages, known as AdSense optimization tips. You get one virtually every month, on the first on the month. Mine have typically said that I should add more AdSense units to my pages.
In this month's release, some AdSense publishers are reporting receiving a tip to add Referral ads to their sites. Here is the message:
Referrals can add incremental revenue to your site.
You are not currently using Referrals on your sites.
Why is this an issue? Well, Google just announced that they are dropping referral ads within the next two months. In fact, Google suggested that publishers remove the referral ads as soon as possible, so why are they automatically suggesting that publishers add them this month?
Automation at its best. :)
Forum discussion at WebmasterWorld.