Operating on only one side?

This is 100% normal. If you have a capsular contracture, that is deforming the shape of your right breast and your left breast is soft and normal, only have your right breast operated on. Why would you want additional surgery on your other breast if you don't need it. There are always risks of complications. If your implants were 10 years old, I would recommend changing them both. But not at 4 years.

Capsular contracture is a complication that can occur after breast augmentation surgery, when the scar tissue around a breast implant tightens and hardens: ExplanationThe body forms a thin, pliable, and translucent capsule of scar tissue around a breast implant as a normal response to the foreign object. However, in capsular contracture, the capsule thickens and tightens, squeezing the implant and causing the breast to feel hard and painful, and look abnormal. SeverityCapsular contracture can range in severity from mild to severe. The Baker Scale is used to grade the severity of capsular contracture: Grade I: No contracture or asymptomatic Grade II: Mild contracture that is painless and almost undetectable Grade III: Moderate contracture with some firmness and discomfort Grade IV: Severe contracture that is painful and can be diagnosed by observation alone PrevalenceAbout one in six women who have breast augmentation surgery will experience some degree of capsular contracture. CauseCapsular contracture is caused by anything that leads to inflammation of the capsule. TreatmentPlastic surgeons can perform breast augmentation revision procedures to treat capsular contracture.