Hey bud... Had the same issue with another guitar from another manufacturer.
You say the dead spot moves as you tune up and down. This to me is a a very good clue that you indeed do have a dead spot and not another issue such as high and low frets. Never-the-less it is worth ruling out other things which may be causing the issue for piece of mind. Including:
Lowering the pickups
Changing the string for a new one
Check the saddle on that string
Tighten everything down and make sure nothing is vibrating in sympathy
Raise the action to a point you can be 100% sure that the string is not touching any frets above
How is the truss rod?
I did a video on dead spots. It's set to private but you should be able to view it via this link:
http://www.youtube.com/watch?v=pJlNV3VF2SY