I do not doubt you at all, but I have to ask the question, and it is in no way accusatory towards you, because I believe you
How much could they possibly charge to fix an oring? In this case, I imagine a lot, if they are telling you, and saying it is outside of warranty.
Why would they even charge anything to simply tuck the oring back in if they ran across such an issue.
Why would they care to do it.
In the long run, the dealership would be better off to tell you they saw this, and took care of it for you, "No charge" because it only take a minute.