It's normal and more common than you'd think. They're called "meat spots" and are just a glitch in the production system. It has nothing to do with whether or not the egg is fertilized. You don't see them in your store bought eggs because those are candles before they are sent to you grocery store. The imperfect ones don't make it to the market. You can use them as is, or you can scoop out the red spot if it bothers you and then use the egg.
Yep, called 'meat spots' or 'blood spots'...it actually is blood, that comes from a tiny broken blood vessel when the ova is released...can also be a tiny bit of tissue that breaks off during same release.