Dodgy ride height?

[Nightshade]

After some mixed results, I thought I'd put my X6 back to Ellis' standard set up and work forwards.
I'm worried about the front ride height though. The set up uses the standard 'arms level', but in order to set mine level, I have to have one shock nut wound down about 6 threads lower than the other. Is this normal? Or indicative or a problem elsewhere? I can't see anything amiss, but I would have thought that shock nuts in the same position would give a level ride height??

Perhaps my eyes are wonky?