If the cracks on ground are not too deep and wide, it should not be a problem. You can ask builder have a look. If it is necessary, ask them fix it. They should do it. You have (1) one month and (2) one year warranty from your builder for new house-- if you feel it is a problem, it is reasonable to ask them have a look, it 's free.
If you really worry about it, ask an inspector have a look ( you can ask him look your whole house), but you need pay for it.