There is always the potential for a gun to go off accidentally, whether it is in a holster or not. It is important to remember that guns are designed to be fired, and even when they are not in use, they still have the capacity to discharge if they are not properly handled. There are a few things that can cause a gun to go off unintentionally while it is in a holster. One possibility is if the gun's trigger gets caught on something as it is being holstered. This could happen if the holster is not lined up correctly with the gun, or if there is something else in the way that prevents the gun from going all the way into the holster. Another possibility is if there is something pressing against the trigger of the gun while it is in the holster. This could be caused by an ill-fitting holster, or by something else that has been placed in the same pocket as the holstered gun. Regardless of how it happens, it is important to remember that any time there is anything other than air between a trigger and its corresponding finger, there is potential for an accidental discharge.