Why are the 2012 cars out in September?
THe championship determines the initial offering of the tags, and therefore shiould be viewed as the "new year" for tags after the meeting when they are distributed.
You can always play for older tags, but I would think that you would want to keep it in the same year. The tags this year with the varying historical icons on them may be a little more collectable to some though.
As for the tags in play, the rules were morphed that the top 10 were supposed to be played in league once a month, this is why the league sheets and some scorecards have TAG # on them, to track the tag to ensure that its not being used as a dust collector at home.
Though I took #3 from St. Louis, and Dan had #12 from there in 2006 I think, and brought it home, so sometimes it is impossible to prevent. I did return to St. Louis though and played and left with #78, they were much happier that day then when I left with #3...