Hey, bcgt350! I hear you -- I don't think anyone likes fees, period, but surprise fees are especially uncool.
Since we can't see your device, we're not the best folks to give you any advice on whether or not a fee will be incurred. Typically, normal wear and tear is not considered enough to void your warranty and necessitate an out of warranty fee. You mentioned you were assured that this would be OK -- was that by the representative who took the phone in the store, or someone on our Care team over the phone?
Ultimately, I will say that if an out of warranty fee is charged, the team receiving the package and assessing the fee should be taking photos of the damage that the fee is incurred for -- and those photos are something that teams with account access can link you to. Hopefully this isn't an issue at all -- but it's just not something we can guarantee, so I at least want to let you know what that process looks like if it does happen!