Diagnostic Tree: Problem Gone?
Why Your Breaker Tripped But Is OK Now
If you have reached this page without beginning at the Start of the diagnostic tree, you may do better to start there.
A circuit breaker tripped and you were able to reset it. Why did it trip to begin with? Were heavy loads (space heater, microwave, hair dryer, etc.) possibly running when power was lost? This would have been an overload, where too much being used on the circuit will trip its breaker to keep the wires from getting too hot. This inconvenience is not dangerous. To avoid it, either adjust your use of heavy users, find stronger circuits for them, or have a new circuit installed for such things.
Another reason a breaker could trip but be resettable would be that something on the circuit had a brief short circuit of some kind that is now gone. Occasionally a light bulb burning out can do this. If the circuit trips in the future, notice the circumstances.
Could your one-time tripping indicate that the breaker is going bad? Not usually. If a breaker goes bad mechanically, it would not let you reset it. But there is occasionally a condition that leads a breaker to trip early from its own heat. This is when its internal contacts or its connection to its wire or busbar in the panel is getting poor. If testing reveals this is the cause of your breaker tripping, the breaker will need to be replaced and perhaps located in a new place in the panel. Otherwise it will be "false tripping" more often as time goes by.