certain classes level in abilities automatically as long as they never train in them.
For instance, if a paladin puts no spec points into Slash or Chants, he will automatically level up 1 in each of these for every 4 levels, so at level 32, if he didn't train in these at all, he would still be 8 Slash, 8 Chants.
It is a stupid thing they did. It encourages people to Power Level their toons to get small advantages over people that level them up the old-fashioned way.
Most classes don't autotrain. Check the herald to see if your class does.