I have a crease under my breast 4 weeks post. You can see it when I raise my arm. Is this normal or is something wrong?

It will settle with highest chances for a smooth contour within few months, this is a quite normal effect at the early days.

This crease will probably relax more with time. It is the original bottom fold of the breast rising up on the implant when you raise your arm. It is not something that you have to revise.

I understand your concern. There can be a number things going on, but I can not tell what without examining you and seeing your before images. Four weeks is really quite early after surgery and might be too soon to be concerned. There is a huge difference in the appearance of the augmentation when I see my patients at one month and then again at 3 months post op, much better at three. Your surgeon would be the best source at this point. Good luck. Hope this helps.BRK