Good morning: I am relatively new to error coins and I have found enjoyment in searching for these coins. I have came across a 1990 cent that looked a little different than others that I have seen in the past. The area in question is at the crease of the mouth. I am thinking it might be grease filled but my knowledge is limited. I am attaching a photo, which I hope is clear enough that the are a of question can be seen with relative ease. Through my loop I can see an extra line next to the lip. The error runs down to the facing of the coin. If this is in fact an error can you advise which error type exactly and is it a type worth getting it graded. Thanks in advance for your assistance in this matter.