There is always a risk of infection in surgery, slightly higher with grafting and even higher with artificial material. Still, infection would be the exception. A severe infection could indeed wreak havoc on your nasal tissues but since this is highly unlikely concentrate on looking forward to the positive changes you will be seeing in the weeks/months to come.
Rib cartilage and infection
Infection is always a risk, but not that common with autologous tissue. Signs include redness, fever, pain, and drainage. Best of luck.