No repairs covered under warranty because moisture found

Hi, I recently took my white 13" macbook into my local apple store because it was not powering on at all. The genius bar representative was told me that my macbook was still covered by the warranty (for 80 more days) and that they would send it to the repair center to repair the issue. A couple of days later I received a call from the repair center representative who told me the repairs would not be covered under the warranty because there was evidence of "spill damage." I explained that I had not spilled anything on nor could of think of any way in which the laptop had been exposed to moisture. Today i talked to a couple more apple technicians & customer service reps trying to get more answers. The technical rep sent me a picture and said he didn't see any signs of a spill but he did see a small corrosive spot in the lower right corner of my display panel. He connected me to another rep who explained that if there is evidence of moisture at all the Apple repair center will not do the repairs under warranty...even if the moisture is unrelated to the problem. I love my macbook and all of my apple products, my friends will tell you I am a huge spokesperson, but I feel like I have been taken advantage of here. I have done all I can reasonably do to protect my laptop from moisture. Does anyone have any good suggestions on how to move forward on this?