warcraft 3 frozen throne bonus campaign cairn last hero ability point

I'm replaying Warcraft 3 frozen throne bonus campaign and I remember that in my previous playthroughs, Cairn the tauren always has one hero ability point missing.

Is that how it's supposed to be? or am I missing something?

EDIT: I will try to clarify, the other heroes which are Rexxar, Rokhan and Chen get 18 hero ability points total from leveling up and clearing quests. On the other hand, Cairn gets only 17. With 18 points I can max out the heroes abilities (3 spells * 4 levels + bonus stats * 4 levels + 1 ultimate * 2 levels). In my previous playthroughs, I get an ability point as a reward from the main quest right before Cairn who ends up missing one point.