Rare or what ?

HI and welcome,

Yes, i have but it's not rare and it's not a disease. It's to do with your red blood cells and could indicate an underlying problem somewhere in your body but it's doesn't specify where. (it could also be nothing at all to worry about)  It happened to me several years ago. Speak to your GP because we are not medical professionals and won't be able to give you any medical advice.