Radiator fan not spinning

Hello everyone, I own a 2003 Honda accord lx with 216,000 miles on it. While she has a few issues (none of which are serious) but today, looking under the hood I noticed that the right radiator fan (right being on the passenger side) wasn't spinning, but the left one was. The car doesn't overheat, but I'm a bit concerned. Should I replace the unit, or an I worked up over nothing?