"Gday Mate,
If it is offset to the right, looking from the tail forward, it is known as right thrust, it is built into the firewall of good aerobatic aircraft to compensate for the torque effect of the prop, You will notice a difference if you don't have it, for a start when you pull up into a loop, the plane will veer to the left, & you will need rudder to stop it from going offline. If it is offset to the left, change it so it is either straight or slightly right, If you have a look in the December edition of Model Airplane News, it shows how to check the amount of side thrust in your plane, page 16 under Tips & Tricks.