what does additional review mean at TSC fro mVSC? Did anyone get

I got a letter from TSC today, indicating they are actively processing my case, however they have to perform additional review on my case. What does it really mean?
MY PD March, 2005, 1st FP 08/05, 2nd May 6, 2007.Transfered on Mary 7, 2007, from VSC to TSC. NC was done on Marh, 15, 2007 (letter from FBI). Anyone has some clues for that? Thanks.