An email had been sent to me later on this morning, as usual I was shocked a bit after looked that the email was sent from Google AdSense .. what I've been doing wrong? But after a glance reading, it just a follow up of their post on Inside AdSense Blog which I have posted before.
In early January, the option to add referral units directing users to the AdSense product will no longer appear in your account. You will continue to accrue earnings for all existing referrals yet to generate $100 until late January, at which point the program will be fully retired. Existing referral units will continue to appear on your pages. By the end of January, you should remove all referral units directing users to AdSense from your pages. Referral units that you do not remove will continue to be displayed on your pages as normal, but conversions will no longer be recorded. We suggest you replace the AdSense referrals with referrals to another product or service or an additional ad unit.
As I wrote, I never put the AdSense Refferral, so have not to pull anything from my blog(s).