Is there a bug with the (inherent) call lightning timer? As it is, you get a timer after using the skill:

You are affected by:
Spell: 'call lightning' for 8 hours.

...snip till it wears off (note an additional blank line between the prompt and "Autosaving"):

You are affected by:
Spell: 'call lightning' for 0 hours.
<prompt> 


Autosaving.

Then, after great many ticks/hours more, you actually get the echo

You are ready to use your racial ability, call lightning, again.

I don't get what the first timer is for, as you can't re-use it before you actually get the echo (didn't try this time, though).

Did you not also see a "You are ready to call lightning again." echo?

Storm giants who know the call lightning spell will get two "wear off" echos because they can cast it again much sooner than they can re-use the inherent ability.