Thanks Annz, unless they do a real nasty job of it I am pretty sure I would be happy with a repair. You have to get in just the right lighting to notice the crack at all but I do not want it to widen. My concern though is whether or not a crack repair is a permanent solution. I would not want to forfeit the chance early in the game of having it replaced. They are coming today to have a look. When I called the gal said wow we have Never had that happen. I find it hard to believe it never ever happened with a marble top install because I do know it can happen. I did not do my normal research and job overseeing because I have used this company before for countertop fabrication and they went well beyond fabulous. However, it was all different employees this time around.

my question would be where is the pool builder and how old is the pool...

I found this repair kit online. So I may give it a shot: MK Hole Repair Kit Buff https://www.amazon.com/dp/B00VXTGSRQ/ref=cm_sw_r_cp_api_i_rrSTDbHVF3N8H

Those are naturally occurring fissures. As long as the top is properly supported these will be no issues.