RG, hadn't seen the gothish pic, but I don't think it's all eyeliner.
My wife, who has a son who is grown and long ago out of the house, is a grandmother 3 times over. First one came when her son was only 18 or 19, and it was a while before we used the word "grandmother" at all...kind of an unspoken rule that I just shouldn't say it. Now she's comfortable with it, but her son is 31.
Still...even as a grandmother 3 times over, she still likes to rock. We've even been to Ozzfest each of the last two years. So I say, rock on and enjoy yourself.