Is 26 AKB48's Unlucky Number?

I recalled recently that during a SDN48 appearance (Show Battle) that they mentioned the number 26.  Is there a specific graduate age of AKB48?  I looked into it.  Cindy, Yukari, and Haruka were transferred before they reached the age of 26.  Noro Kayo and Megumi Ohori were both about the age of 26 when they were transferred, and they were the oldest members of AKB48.  So why do I bring this up?  It is not to discuss the whole issue of idol groups trying to stay young, but a certain someone is approaching the dreaded number.  The oldest member of AKB48 is currently: Shinoda Mariko.

Shinoda Mariko is 24, two years to go.  But, what about those who were transferred before they hit 26?  Could it be that they were moved to help SDN48's debut?  Shinoda is one of the most popular members of AKB48, so it would be hard to transfer her (even if you don't consider if she would be even willing to transfer).  Then if you think about it, both Yukari and Cindy were also senbatsu members.  If you are not concerned enough about Shinoda, Yukari and Haruka were born in the same year as Sayaka, Yuko, and other members of AKB48.  Akimoto has already stated that Yuko has years until she would need to graduate, but she is the most popular member right now.  Sayaka, on the other hand, has dropped in senbatsu and general position.  The producers have moved Sayaka to an Undergirls spot.  The teams were shuffled recently, so it is unlikely that there will be anymore transfers or graduates right now.  Just something to be concerned about for the future.