I think maybe at a minimum, just a CYA in case nothing else works, I would write a letter (sent certified mail) to the dealer explaining the situation and saying you are positive this is indeed a valid problem and it should be covered by warranty and that if something does happen in the next few months when it comes out of warranty you will expect them to cover it. Tell them that they have been hereby put on notice that this should be a warranty problem and they refused to fix it.

This would at least give you some ammunition to come back later and say "see, I told you so back then that this was a problem - so now what's your excuse for not fixing it under warranty?" And they can't say "sorry, there was no problem - what are you talking about?"