Middle of Summer Sausage brown

What is your recipe for summer sausage? It sounds like you had no cure in it or not enough. Also it might be that you did not allow it to cure long enough. These are just a few thoughts. Welcome to the forum.

The recipe was a complete package from Cabela's.
It is the first time I have tried it. Have not had this problem with other recipes, but still not ready to place the blame there.

It is the cure process. Make sure you mix the cure in 1st and by itself. If you allow it to mix to lom=ng the muscle texture will start to break down and not have a consitant texture. The only other possiblity is that you didn't get enough cure in the product or not mixed properly. The reason you mix the cure by itself, is the cure has certain property that react to other spices and it could deactivate the cureing process.

Thanks for the input. Now, that it may be a problem with the cure, is the sausage safe to eat?

You need to first make sure back when you cooked it did the internal temp reach the safe zone of what ever the meat block is you used. Second the most widely used method is the sniff test. If it smells good it will be good. But just because you have a brown spot doesn't mean its spoilt.