H1B petition approved for more than 6 years


I have received the approval notice few days ago for my H1 extension and I
was reveiwing the approval notice and saw that the extension has been
granted for 10/01/2012 - 04/21/2015. In my case, during the initial
filing of the application of my H1 extension in the month of June my
employer requested till Feb 2014 per my max out date but during my H1
extension application was pending with USCIS, my I-140 get approved
…a little background, due to processing delay we converted H1
extenstion to premium processing and received RFE which my employer
responded and get approved… so do you think since my I-140 was
approved USCIS gave me the expiry date as 04/21/2015 as I am eligible
to have H1 more than 6 years based on I-140 approval or do I need to
do anything ? Thought of checking with you and get your advice…

Thanks in advance,