I'm trying to put myself into your shoes if this were to happen to me with the LBS that I frequent. I own two bikes, which almost sounds like the start of an inverse Twelve Step Program--one that increases one's bike purchases.
My Kona Dew is a 2007 that I bought in mid 2008. That was a different LBS from the one I frequent now. Nothing wrong with the LBS, but I'm living about 40 miles away so I no longer go there. I don't recall if the tag indicated it was a 2007, and I don't recall them telling me it was a 2007 model. It ain't like with automobiles. The product turnover isn't the same, and there are no laws that I am aware of governing the sale of bikes and the publishing of the model year.
If the bike was not previously owned when you bought it, then it was technically new. It is not unheard of for a new bike to be sold out of an LBS, even though the bike is several model years old. There is another LBS near me from which I have heard tales of brand new, still in the box, bikes in their inventory that are 10 or more years old. It is an odd place.
30% off of the original price doesn't strike me as unreasonable, if the bike was not previously owned when you bought it. If the bike has been good to you, you are happy with it, and otherwise happy with the LBS, then don't sour that. I would recommend that you visit the LBS, with the bike. Be honest and polite and just ask. Don't go in with an attitude or making any threatening sounding noise, like asking to speak with a Manager or the Owner. That tends to make any business more on guard and defensive. If you treat the conversation casually, then it's more likely that the LBS will.
"Heh, I bought this bike back in June, and I've been very happy with it. I went to register the frame on the Moots website, and I learned it is a 2012 frame. I just wanted to ask whether it was previously owned."
Then shut up and let them talk. The person you talk with likely won't know, so give them a break if they say, "I really don't know."
Remain polite, but be a little persistent. "That's cool. Is there any way you can check?"
Maybe they have a computer system with sales and inventory and they can look up the purchase, the bike, or both. Maybe they haven't joined the Paperless Society and everything is in filing cabinets. Whatever the case, gently push to find out if the bike was previously owned.
If it was previously owned, then you have to consider whether the price you paid was a fair one or not.
I would not expect the LBS to offer you up any money to offset what you paid for a used bike. They might be willing to inspect the bike for any signs of serious wear, but even if they are then they are entering into a very delicate area.
For argument's sake, let's say the bike was previously owned and there is noticeable wear. Now what. Did you put that wear on the bike or did the previous owner? There's probably no way to tell.
Again, if the bike was not previously owned, then in my view 30% off of the original price is a fair deal. If so, call it good.