Does your chicken lay pure white eggs normally or are they sort of tan colored?
If the eggs are normally pure white, there may be cause for concern. If her eggs are tan or light brown, then the "blood" you see is from the color a hen lays down after the shell forms in the egg gland. The color is produced by a hen's body using discarded red blood cells. Sometimes the color comes out "streaked".
I have hens that lay red eggs and the color sometimes looks like the picture of the egg you posted.