What Causes Blood In Urine Post Gall Bladder Surgery?

My hubby had a surgery to have the gallbladder removed. After surgery, his penis was inserted a urinary catheter because the nurse said he is not peeing. Later he peed and the color was normal yellow. Before leaving the hospital, the nurse inserted a new catheter and at home, I noticed the color of the urine became like a bit reddish and there were bloods inside the tube. Is this infection or the tube was not properly inserted?