Not sure if this is a bug or not

Hi, i am having a problem with one of my mounts and that is i can't learn it. (the mount is the blue dragonhawk which you get from 100 mounts achievement)
It says you can never use this item and i don't understand the problem so if someone can enlighten me on it i would appreciate it. And please don't make a sarcastic comment that is way too obvious. But i could learn the Red one but not the blue one.

the red one can be learned by Horde, blue one by Alliance. I guess you can now understand why.

Anyway if you throw away the Blue mount from the bag and then Relog, it will be automatically learned from that character.
If you check your other characters you can see they all already hove both mounts, Blue and Red one.

Thanks alot :)