Definetly agree, if its broke already send it back.
Something that has always bugged me is that my Kermits right foot has a hard patch on it, feels a bit like glue, its not visible, but I know its there! As a perfectionist with these things, I was almost afraid to return it. I bought Kermit, then won one, the one I have is the one I won, The one I bought had eyes far to wide apart and hence he was sold on ebay, so although I have a non visible defect on the feet he is perfect otherwise. If I changed him, he may have other worse defects.
As you have modified Animal, you may face problems, but I doubt a customer service guy at a company would even notice the changes, I guess you got it from collector zone, so email them and see what happens, you dont want Animal with a broken jaw? Also, the paperwork included is some sort of guarentee! Imn sure you can get is exchanged?
Chris