Is the son sinful if his mother gets upset by his calm words?

If a son adopts respectful dialogue with his mother and does not intend offense in what he says or does that displeases her, then there is no sin upon him. This is based on the general meaning of Allah's saying: "Your Lord is most knowing of what is within yourselves. If you should be righteous, then indeed He is ever Forgiving to the often returning [to Him]." However, he should still seek to appease her.