That's pretty normal. For whatever reason, they seem to give you a little more than 12 months, depending on when during the month you purchase it. I believe if its in the first couple weeks, then you get the rest of that month, plus 12. In the latter half of the month, you get the rest of the month plus 13. I used to think it had to do with how they processed the cards in groups, but now that they are printed on demand I'm not sure...
The TIW cards don't track your AP at all - you are just eligible to get one. You could get one on your last valid day of your AP, and it will still be good for 12+ months.