A Samsung spokesperson said to Engadget that “We are looking into a limited number of reports of Galaxy S9/S9+ touchscreen responsiveness issues,” and encouraged any owners with problems to contact the company directly.
“At Samsung, customer satisfaction is core to our business and we aim to deliver the best possible experience. We are looking into a limited number of reports of Galaxy S9/S9+ touchscreen responsiveness issues. We are working with affected customers and investigating.
We encourage any customer with questions to contact us directly at 1-800-SAMSUNG.”
https://www.engadget.com/2018/03/22/samsung-galaxy-s9-s9plus-dead-spots/