Bricks, Masonry, Asphalt and Concrete - Cracks in concrete slab

We live in a single story home on a concrete slab in California. Flooring guys pulled up the carpet today to start installing hardwoods and says there are cracks, some of the worst they've seen and some settling. (1/4 or so)

I talked to the guy on the phone (still at work) and they seem to think they can grind it a bit and shim as needed and there is no need to stop installation.

I am wondering if I should call in a concrete specialist to evaluate the problem before the floor gets installed.

We've been here 10 years, and had ceramic tile laid in the kitchen directly adjacent to the living room where the cracks are and the tile in there is perfect.

What should I be looking for when I get home to determine if I need to call a pro in?

Thanks!

That's a tough call. You say you were in the house 10 years, but how old is the house? Those cracks may have happened 50 years ago and pose no real problem. However, 1/4 inch settling would give me pause. Good luck.