What Causes Muscle Injury During Breast Augmentation Surgery?

I had a revision breast augmentation surgery two weeks ago. My surgeon told me while he was lifting the the muscles to replace the old implant from top of the muscle to new implants under the muscles , there was an accidental cut in the muscle which he then had to repair. It took him double the time to do this surgery . He has now told me I should not massage the breasts like every implant needs to avoid capsular contracture as he is worried about the injured muscle. How serious is this? Will it heal completely and would I be able to resume normal activity without damage to my breasts eventually?