iPhone 7 screen popping out on left side

I have had my phone for 7 months, second hand. Since purchasing I have dropped my phone a total of 2 times, one being before and the other after I got the battery replaced in the Apple store. I was wondering why when I put a new case onto my phone the screen suddenly popped up on the left of the phone, could it be because it hasn’t been put back properly after battery service?