15F is purple blood during the middle of a period normal?

I (15F) noticed that the blood that absorbed itself into my pad was a purple color, not red at all, and i wasnt wearing that pad for too long. I am on the 4th day and my periods usually last 7 days. When blood is dried, it's usually dark red (or dark brown if it's at the end of my period), but never a clear purple color. I haven't had this happen before. Is this normal?