Hmm, Im sure I saw the spiral, but I apologise if I was mistaken. My roguish knowledge is very limited.
Edit:
*Bows down to better knowledge* .. Just checked again and can confirm no cooldown spiral so it is as thebigmunch said
So, although not on the global cooldown where you aren't necessarily in range for a melee hit it may not work every time
Did I understand it better that time ?