The UV's look fine. I've noticed them on bits I did at the start now as well (they were a lot smaller so I didn't see them earlier)
I'm making the bump map in photoshop, drawing all the lines by hand with the brush tool.
It definitely seems to be a problem in maya as they don't appear on the image file itself.
I'm rendering with mental ray
I'll try a different file format and see if that helps

edit: come to think of it, I did have to change the UV's slightly (although not on any part that I had already bump mapped) so I'll try reassigning the shader as well.