Zodiac sign change only if born in or after 2009?

Apparently, as I am sure you are all aware, a thirteenth zodiac sign has been added which changed the dates of all the rest of the zodiac signs. This changed the sign of almost everyone, besides a few exceptions. I have heard from several people that the change is only valid if you were born in or after 2009. I was wondering if this was true, since I haven't seen any evidence to back up these claims. If anyone DOES have evidence, can you please post a link with your answer? Thanks so much in advance :)