Man that is so tough. You do not want to look like a tattle tale but you do not want to be blamed for bad work. Did you receive any feedback yet? Would it be possible to see your boss and say something like " do you have any feedback on that project I worked on with mr x?" and then wait and see what you hear? But even then it would still probably sound like you were just trying to dime someone out. Personally I would wait until something is said to you. If nothing is said move on. If something is said be careful how you word things. Make sure to "own" some part of it even if it really isn't yours to own because all bosses feel like employees have some part to play in a screw up. But you can own something without taking the fall as well.