I'm not really sure why some doctors do it one way and others do it another.  I think it boils down to preference.....their preference.  And any good plastic surgeon will tell you that to get the most natural feel, the implants should go under the muscle.  Now why you would have to start over is beyond me, but I'm thinking it might be because the pocket between your muscle would need to be stretched before an implant can be placed there.  I can also tell you that the 'old' way of doing implants was to place it above the muscle.  I'm not sure when the procedure changed, but I'm thinking it was in the last 5 to 10 years.  Some surgeons are just stuck on doing it the old way cause it may be easier for them, or because patients are uneducated and don't know the difference between over and under to request them a specific way.  I can tell you that you would probably prefer them under.  I have mine under and they are real soft given the fact they are implants.

Good luck!

Angi