That's how I age them too, not many people know and when selling often say they are younger. Mine was stamped 10-98, so you will see similar digits (October, 1998)
I'm not sure I know who you are Moana, but as others have said I have never owned the horse in question. If you know me, then I think you might have your wires crossed as I did have a Seren years ago, she was a grey cob x hanovarian, and I also had a black sec D broodmare who was called...