Is it normal that every time I lift or flex my pectoral muscle my breast implants move?

I had breast augmentation under the muscle 4 months ago. I was a small A cup and had 360cc put in. I noticed every time I lift or flex my pectoral muscle my breast implants move and sometimes hurt if I lift heavy weights. Is this normal? Would it go away? I’m not sure if I’m liking how the implants move and contract with the muscle.