Its kind of a normal thing. Some people just get really o.c. about it. Even with the tank empty, its still a heavy chunk of metal.

Grab some poly spring spacers from your local Old Man Emu or Ironman dealer. They sell them starting at 10mm. They are usually used to level out the difference between front ride height and rear ride height but you can also use them to level side to side differences. Try some on the left front spring just to see.