Yep, you upgraded from an HD receiver to an HD-DVR, that means a new 2 year contract. As far as getting a refurb HD-DVR, that is just the luck of the draw, you get whatever the tech has on his truck, sometimes it's new stuff, sometimes it's refurbs. As long as it works DirecTV gave you what they said they would give you.
Cable companies do the same thing, very rarely will you get a brand new box from the cable company, you will usually get a used box that someone else turned back in before you. At least with DirecTV they try to keep their equipment somewhat up to date. Comcast gev emy parents an HD-DVR with a hard drive in it that can only hold about 20 hours of HD, and say they don't have any with bigger hard drives in their town.