Vinyl Plank Flooring

We built our home 3 years ago and had Nafco vinyl plank flooring installed by our builder. After about a year some of the flooring started to come up at the seams. The builder came in and replaced some of the planks but now more are coming up. We have quite a bit of our house done in this flooring. We had the carpet/tile store's manager come over and he said it looked to be the builder's problem. I feel it's a plank problem since it is coming up all over the house in places. We are still under warranty - and I feel it should be replaced. Any ideas or suggestions on what else it could be?