Blood in the semen may be caused by inflammation, infection, blockage, or injury anywhere.

Bloody semen is almost never serious (or, as many people first think, a sign of cancer).

It could be testicular or prostatic.
Personally if he is not in pain and has no obvious signs of infection or injury I would wait until monday and see his regular doc, other wise yes do seek medical attention.

If you wait until monday, don't then put it off. It should be investigated for peace of mind.
A bit like a woman finding a lump in her breast - you don't need to go to emergency but you do need to be looked at in the very near future.

We weren't having sex, but I was giving him a hand job and when he came it had blood mixed in with the actual cum. Since this happen does he have to go to the doctor or will it just pass? Both him and I were and are completely scared. If anyone has an answer please clue us in.

Try reading my reply above. It answers your question fully.