I had surgical procedure today and nurse gave me one norco for pain afterwards 10 hours ago. is it out of my system? is side effect / risk of stopping breathing still a chance? that scares me?

There is zero risk of such problems with the normal post-operative doses; and if there were a problem, it would occur in the first 30 minutes after the dose, no later. Nothing to worry about. Discuss with your doctor if you remain concerned.

One Norco, which is a lower-potency narcotic, would have no real potential to cause any significant danger on its own. Apnea secondary to opioids becomes a risk when mixed with sedatives, tranquilizers, sleeping pills, and barbiturates. Gather this is NOT an issue for you.