bought my open box MBP 15 on MARCH 11 2013. this is a mid 2012 model (so it was produced in jun/july 2012).
sent in my receipt to apple, apple changed the warranty date starting March 11 2013.
even better, the computer came with Lion OS, so I called apple asked about the free update to Mountain Lion OS promotion that they had going on. apple gladly gave me a free code to ML.
even better, every mac 2011 *not sure* or newer gets ilife for free. because the ilife has been used up by the last purchaser, apple gladly gave me a free code to ilife.
i'm happy with a smile getting 40% off the retail price.