Squeaking of the breasts after surgery is rare. There are two reasons why this occurs:
1) If you had saline implants, it is possible that your implants were underfilled so that the water within the implant is swishing around, but this is probably not the case.
2) The more likely cause is that the dissected pockets are larger than the placed implants and so that the implants are able to move around in the pocket. Within 2 weeks following surgery, the pockets will tighten down around the implants and the squeaking will resolve on its own.