No, Izzy. A nineteen year old is fine. Any story that is posted must have characters, either fictional or real, that are 18 or over. Last September, on Hilary Duff's 18th birthday, I added her to the tickling baseball team , at midnight on Sept 28th, with a disclaimer posted in my first story about her, making reference to her real life 18th birthday, and all was fine, no removal, or action, from any mods, or admins. Just be sure any character, real or fictional, is 18th birthday, or over, and all should be fine.
Mitch