House is 4 years old but has problems - too late to go back to the builder?

Our house is only 4 years old. It came with a 1 year warranty but we are starting to notice many problems. Cracks are appearing in walls, nails hidden my spackle are popping out and when roofing shingles came off the house, a roofer said the shingles were not properly nailed. It is too late to go back to the builder and ask them to resolve this? I know people will say to get an attorney but that is just more money. You would expect some kind of umed warranty when it comes to a brand new house.