Check the wind direction when taking off,it may be a default flight thing as well.
As far as being centreline on the runway I wouldn't worry too much as long as you're on the runway

The other thing is,are you looking at the runway from the cockpit view and then changing to spot view? If you are then you will find with different aircraft and addon panels that the two views will not coincide. To centreline the aircraft taxi it in spot view to line up the nosewheel on the centreline. Go back to cocpit view and have a look at where you see the line from there.
Next find a reference point on the panel that lines up with with the centreline(I use the outermarker light on one panel and the end of the upper control section on another) This will give you reference points to maintain centre(not applicable in windy conditions 'til you straighten up to touch down) It will help you correct on takeoff and give you an advantage at touch down-yes you can put the nosewheel on the centreline

White on White fly all night.
Red on White you're alright.
Red on Red you'll soon be dead.