RMA replacement drive warrnanty

I got my repalce Caviar Black WD1002FAEX drive instaled.  I then went to register the drive only to find 110 days of warranty, compared to 1622 for the “original” drive.  I have seen other posts stating the warrnty period will be updated when WD tests the returned drive. 

I sent it under the standard RMA and not the advanced RMA.

What will happen? 

Contact WD, they will update the warranty for you.

To Contact WD for Technical Support
http://support.wdc.com/contact/index.asp?lang=en

They are of no help!   They just state “wait” for the warranty period to “change.”  

How can a Caviar Black with a manufacture date of December 25, 2010 only have a warranty period @ 100 days?