Noisy breaker, whats the reason
Last thing you want is a dodgy circuit breaker. I suggest that you replace it so when and if you ever have need for that breaker to protect a circuit you can depend upon it to work properly. 

I got the impression from reading your posting that you are using this circuit breaker as a regular switching function. Be aware that some breakers are not intended to be used as regular switches. Others may be designed to work correctly. Please see the accepted answer on this posting for further information.