It's common to replace your clutch release fork if it shows signs of wear, appears bent or shows cracking under stress. Even the best looking release forks may often fail. If your clutch has had a very 'heavy' feel to it prior to performing your clutch job, then you might have placed a lot of force on the clutch release fork, which has a tendency to weaken it. It's good practice to replace it while you are doing a clutch job as it is a relatively inexpensive part. Also replace the pivot pin at the same time for extra insurance, and do the job right the first time.