If this is the only location that is cracked it will not cause the house to fall down, it is just and eyesore especially on a new house. If you can contact the original contractor, even though the 1 year warranty has passed, he should come over and repair it under warranty. It looks bad on the contractor and just a little bad word-of-mouth can be very damaging to him.
If he won't talk to you, you can break the cracked portion out, clean the space with a stiff brush and water, brush on an epoxy bonding agent, make some very stiff sackreet and apply it to rebuild the corner. Use a damp sponge trowel to rub it to the existing concrete. Keep it just damp and rub it in with the sponge several times at 1/2 hour intervals; this will keep it from drying out too quick and re-cracking.