I would add to keep it from moving in the future, take a flat head screwdriver to the empty slots that your coil sits between - that is the same metal pieces that the tube is attached to - and pry them out slightly (too much torque can break them off). The makes the centre tube a tighter fit and less prone to go off centre.
This slight mod is written about in threads on rebuilding the nova all over ecig forums, if you need a visual reference check pbusardo's review/rebuild of the nova. He does the same thing in it.
Since I've done this my nova has handled itself much better, be careful doing so as I broke one head by prying too much, hyst a slight torque to make the tube fit more snug.