Iphone restarts itself after pressing buttons

Hello, I'm currently using an Iphone xs max on ios 14.3. And i was just randomly clicking the volume and the sleep wake button repeatedly and my phone suddenly went blank and restarts itself. I know that to hard reset you need to hold the side button for 10 seconds and the "slide to turn off" will pop up before it hard resets. but mine just suddenly restarts itself after clicking buttons. Is there anything i should be worried about? Does this happen to anyone or it will happen if i press buttons repeatedly? Thanks a lot..