Yeah it's not working as intended yet. Instead of always showing up and seeming trainable yet not working until the correct level, it doesn't show up in the list at all until you're of the correct level.

But you still get it at the correct level, its not like you're deprived - the SK guildmaster is just being a douche by holding back the info :(

Correct.

It shows up for each class as soon as you are sufficient level to learn the skill.

(The earliest it shows up for anyone currently are int casters at level 4. Before that it's missing from the list for everyone.)