Thanks for the tip, Ccrew! I'll pursue that as suggested and see how it goes. The Apple rep indicated on the phone that Apple had made the policy adjustment recently, back in December and offered to consult his manager to see if there was something they could do to at least offer a partial date adjustment or something but then came back, no dice. I expect I'll get the same response here but we'll see. It's worth a shot I think.
Actually, I'd go back to Best Buy and ask for a price adjustment if they didn't. From their site:
"Open-box products are returned by customers, served as store display models, or were opened for inspection due to package damage. They are tested to assure proper function. See store for specific warranty and return policy questions. Clearance products include new, unopened, factory-sealed products that are either discontinued, overstock, or end of stock. They come with the original manufacturer's warranty."
I'd read "original manufacturers warranty" to be 1 year from the date you purchased, not 1 year from the date someone else did. Contrary to the jump up and down methodology I've seen suggested here I'd approach Best Buy calmly and methodically with their policy in hand if Apple denies it. Can't hurt. It's not like they don't frequently discount open box items with coupons, and store managers do have pricing discretion. Shoot for a discount if nothing else to offset the cost of Applecare.