Bizarre Hunter Math?Follow

This was odd - maybe it's expected and there's a reason for it but I can't find it.

So I'm dinking around on my hunter last night and I note that it's time to train the pet.

My pet had 110 training points and had Great Stamina and Natural Armor (50 and 75 TPs respectively though I may have that backwards) available to train.

So I figure - OK Armor. Train Armor for 75 TPs

I have 85 TPs left.

Hold on, lessee: 110 minus 75 is... 85???
OK cool whatever I'll train stam for 50TPs then.

Now I have 65 TPs left (or something)

85 minus 50 = 65?

What the hell?

Lets say you need Rank 8 next.
-Rank 8 costs 80 points.
-Rank 7 cost you 70 points, rank 6 was 60 etc etc.
-You need only 10 points to get rank 8 as long as you have rank 7 already.
-You would need 20 points if you only had rank 6.
-However you would need all 80 points if you hadn't trained at all yet. Or you respecced your pet.

Ahh ok that makes perfect sense and I probably should have thought of that. Sorry! And thanks for the info.