I'd review with the contractor.

Not an expert, but the concrete I've placed, and concrete I have had placed by others has not shown cracking like this.

Looks like movement -- likely settlement, in the base material.

Yeah, seems too soon for that many cracks.

I would call the concrete supplier and ask if these are shrinkage or settling cracks. They will have a correct record of the mix, temperature, pour time and if water was added to the mix.

All concrete cracks; it's the nature of the beast. No contractor in his right mind would guarantee against it. Nothing to worry here.

Check out these two links for more information:

Why concrete cracks

Acceptable crack widths

"reliable contractors will warrant their work against a crack this soon."

And will be soon out of business and bankrupt if they do. This is completely normal. It's like complaining that your car tire is round.