1st time it happened our 4 week old puppy of 13 in the litter just pee and it was red. All the others are OK just him. But he is still running around and playing with the others. Should I be concered or just keep and eye on him for a while? He is eating watered down dry food and drinking water from the bowl also we the mom feed them 5 times a day. Nothing else seems wrong with him and it only happen this one time. All others are fine. Just was wondering what should I do?

If he does this again please take him to the vet. He may suffer from an internal injury.

Don't wait for him to do it again - take him to the vet. They should be getting dewormed around now anyway.

Thanks for the advice. Just to be on the safe side I called the vet and she said that if I don't have the money to bring him in then a table spoonful of canberry juice could help. So before I did that I watch the others pee and it seems that the paper is fading with the red die on it. LOL. I was freaking out over nothing. But I just gave them carberry juice anyway ( 2 days ago). And today we dewormed them too. So they got the best of both worlds. But anyway Thanks for the advice everyone.

Good!

But.. sorry, you have 13 puppies and couldn't afford to bring one to the vet?

I'm glad you figured out the problem.
Have you found out how much your vet charges for vaccinations?
They will all need to be vaccinated and wormed before they can go to their new homes.
Some vets do give a discount for a lot of puppies but it depends on each individual vet... shop around.