Yes. The babies has a little muscle in their stomach that is weak and not fully developed when premature. It causes the milk to force it self back up. Allot of hospitals have supplements to weigh down the formula and also allot of them have donated breast mill which is softer on their stomach and less likely to cause gas. It's important to not lay him down for atleast 15-30 minutes after each feeding if possible.
Yes that's normal you probably should also try a different kind of formula I think its like gentle or sensitive so its easy on baby tummy my niece was like that all the time and changing the formaula helped wonders but give your baby some time since he is a preemie
Good luck mama and congratulations