Just experienced this random glitch in iOS 11.3 which I have never seen or experienced before. It was really random and the icons just shifted over but it went right back to normal. I managed to take a screenshot right before it went back to normal.
Never experienced this. However, iOS 11 is full of glitches and bugs, don't expect it to be flawless. Experienced other random glitches. Not to worry about as long as you done experience all the time.