Well, if you opened this i'm assuming that the answer is yes.
call sprint (*2) and tell them you heard about the extra 300 minute promo online and you want it added to your account. It doesn't affect your contract expiration or any discounts you have.
I'm Ben, and You're Welcome
Sprint Launching Tiered Embedded Device Data Plans - BriefMobile
Everything Data 450 promotion - xda-developers