Gmail users haven't entered there birth date in there Google account will see a screen like this, Ensure that your accounts doesn't get disabled

http://www.gtricks.com/google-tricks/google-asks-for-birthdate/

This has been written by Herin M_aru & not Abhishek.
http://plus.google.com/101452691700898909870

[added underscore to prevent indexing of name, as per wish of Herin. -Philipp]

You might had entered your birthdate, in case you are registered for youtube or orkut or google+ or just have a google profile