Is it normal for breasts to "settle" or "drop"at different rates after a breast augmentation? I'm 3 weeks post op.

Thank you for your question. Your plastic surgeon will always be your best resource when it comes to an accurate assessment of your situation, advice, predictions, and/or meaningful reassurance.
Generally speaking, breast implants will "drop" into the pocket that was created during surgery and massaging the implants downward may assist in the dropping of the implants after surgery (for those patients who want to help with the settling of the implants). The rate of breast implant "settling" may depend on factors such as size of breast implant pocket dissected, tightness of the overlying skin/muscle layers, size of breast implant utilized, and concerns such as pre-existing breast asymmetry.Normally, it takes about 3-6 months (for some patients longer) to see the final result. It is very common for one side to settle faster than the other.
Sometimes, one or both breasts implants do not settle as planned and revisionary breast surgery becomes necessary to improve the outcome. On other occasions, if the long-term breast asymmetry is mild ( understanding that absolute symmetry is very rarely achieved), patients will need to decide whether proceeding with revisionary breast surgery is worth the potential downsides associated with additional surgery.
Again, best to follow your plastic surgeon for more specifics. Best wishes for an outcome that you will be pleased with long-term.

Hello, it is not uncommon for implants to settle at a different rate; after several months you will have a better sense of the final result.  It sounds like you have a supportive PS who is following the issue.