In my limited experience with brown sugar, it doesn't impart much color to the cider, so if your cider is brown, it indeed sounds "maderized".
Among my 2012 and 2013 apple, berry and plum wines, none of which were treated with k-meta at bottle up but the head space was kept to a bare minimum, the berry and plum wines maderized in the 1-2 year old time-frame, and (knock on wood) the apple wine barely shows any signs of maderizing. It was easy to see and smell that the wine had maderized.
Per Yopper, I now add k-meta at bottle-up to extend shelf life. In the coming years I'll see if the k-meta helped.
--SiletzSpey