My ducks bills looks bruised but Im not sure, please help!

When I put my ducks back into their pen for the night I noticed that one of them has a bruise with a cut but, it's not bleeding and he can do everything he usually does so, I'm not sure if it's an emergency or not. Please answer if you know if its fatal or not. (Sorry, if I sound unreasonable im just a very easily worried duck mom)