Chosen Solution
I recently bought a refurb iPhone 8 that looks in mint condition. Only a few days later it accidentally fell onto the floor, and one corner of the display separated very slightly from the case - it was more something you could feel than see. I snapped it back into position and it all looks and works fine, but can I/should I assume that any separation at all means that the water resistance has been compromised?
In theory - yes. Most amounts of separation will likely mean that some amount of water resistance has been compromised. It depends entirely on which components are in the “compromised” area when it comes to whether you actually gain any risk on this. Generally I wouldn’t be too concerned about this though, as it sounds like you have pushed a loose clip back into place, which will most likely keep most of the water out. I wouldn’t give the phone a bath in the toilet or something like that though ;)
