I have an OTTR she is going on 15 years old and she is in great health. She has had three pregnancies and three perfect births. She has no health problems and has good weight on her. Last week when I put her morning feed in her slow feeder box I notice a piece of tooth. It was flat and about 2 1/2 inches long. I know that colts shed caps but I never heard of a horse her age losing teeth. She has never shown mouth problems and her last float was good.( six months ago). She doesn't drop feed or "gap" when she eats. So my question is, is this normal or do I need to be concerned?