The post holes often follow the curve of the top when being drilled (though they shouldn't).

If so in this case, it means that the posts splay outwards. Loosen the strings, take the bridge off and screw the posts right down. The tops of the posts should now be a bit closer together, which should allow you to put the bridge on and increase its height if necessary.

If the posts are basically parallel and upright, and just drilled that bit too far apart, then drilling out the holes in the bridge with a drill just a bit bigger than the current hole should help (a 0.5 mm step up or possibly an imperial size if it's smaller and you have one) Drill slowly from the bottom and you should be able to stop just below the top, which will partially hide the drilling.

I'd probably use a black Sharpie to colour the bare metal rather than try and paint it. I find a black Sharpie works wonders on touching up scratches on all black hardware.

If the posts are angled inwards then the posts will get tighter on the outside/end edges of the holes as the saddle is screwed down. Just widening the bottom of the pots holes may be enough. You could drill, but I might try using one of the thin conical sharpening stone bits that normally come with a Dremel to just widen the outside edges at the bottom.

You want to keep any widening as minimal as possible as you don't want the saddle too loose on the posts.