lines problem on repaint

I've been commisioned to do a repaint for a Virtual airline, and all is going well. Fixed some rather large issues, but one is really causing me headaches.

These lines do not show up when painting, they only appear on the model. any ideas as to what they could be and how to remove them, as it looks really bad and the va are unlikely to sign off this specific plane repaint with this glitch!!!
Cheers
Fsnovice

These lines do not show up when painting, they only appear on the model. any ideas as to what they could be and how to remove them, as it looks really bad and the va are unlikely to sign off this specific plane repaint with this glitch!!!
Cheers
Fsnovice