Can a bloody orange be half bloody?

I've got a "sanguino moro" (bloody/red) orange, but it appears to be only half-bloody, as in the photo below. However all figures I've found on the internet show oranges that are purely red inside, for instance the ones on Wikipedia. Is this normal? Should I be worried about it? I'm mostly concerned whether it's a sign of the orange being "sick" or health-threatening in any sense.