My cat Charlie is 6 years old. Just today we noticed that the fur around his mouth is always wet and his tongue has some strange coloring in the middle of it stretching from side to side. My daughter says when she opens his mouth she sees white all along the back of his mouth but I can't get him to open his mouth wide enough for me. He seems to be fine otherwise, he's been laying with us and purring and doesn't get irritated at all when we open his mouth. Does anyone know what this may be or if I should be worried?