I don't think he "apparently died". Nothing indicated that he had passed on after eating the flowers. So why was he delayed in answering Littlefoot? Well think about it. He had been sick for a while, and was tired. Earlier in the movie, he had almost collapsed in the waterfall area because he was exhausted from the illness that was developing. So it made perfect sense for him to not answer Littlefoot right away. He was still very tired.