The excuse will be "it will weather down" It won't.
Yes you should bring it up now as once you have moved in they will have zero incentive to do anything about it.
Also, you will lay down a marker to the site manager that you will not be accepting his usual rubbish standard and if he is not a complete idiot he should try to ensure your new home is better than others.
The solution is to have the areas tinted so the banding is less obvious. Not even the NHBC would sanction have the brickwork taken down and re built so this is the only outcome.