Glow says my period is late?

Sabrina • 22, Criminal Justice major, and with my boyfriend for almost 4 years. Our dog is our kid!
My predicted period was the 13th, but I started on the 12th meaning I was early... A little notification pops up on my period calendar saying it was late. Not TOO important but irritating to see when I know I wasn't late and can be confusing for me later on if I have to refer back to the calendar. Happened to anyone else?