They used rebar in this home as they do in all of their homes. The
builder has a very good local reputation. And in this development is the
biggest builder by far.

Out of curiosity, I checked how the warranty addresses these types of
cracks. And it jives with what J A said above. Minor cracks are common
in the floor and walls of solid pour construction.

Up to 1/8 inch is ok in solid pour walls. Above that and a claim should
be filed. And up to 3/32 in floors with no more than 1/4 inch vertical.
As I said, I'll make a half of a big deal out of it before my bumper to
bumper is up. But these are no where near that size.

The warranty says if they are above those sizes, they surface repair
them unless of course they affect the structural soundness.

I would never retain an attorney or make a big deal out of something
like this (especially based on someone's vague post) unless I researched
several sources.

But I must admit I thought solid pour was infallable..