Is it normal one implant dropped before the other?

Dear dmarie_12,I always tell my patients your breasts will be sisters not twins. They can heal at different rates and "drop" at different times. Dropping of implants is part of the healing process and this occurs after the tissues surrounding the implants slowly relax, allowing the implants to settle into their final position. It can take about four to six months for the implant to drop down to their final position.I understand that you are worried about your implants are not dropping as expected. However, you are still in the early phase of the recovery period. Please do allow some time for the healing process to occur. If after six months, you are not satisfied with the appearance of your breast, you can visit your plastic surgeon and discuss your concerns.Daniel Barrett, MD, MHA, MSCertified, American Board of Plastic Surgery Member, Am. Society of Plastic Surgery

Not only is this normal it is more often the case than not with smooth round devices.  The two halves of the human body are not mirror images and will respond to surgery with disparate amounts of pain, wound healing, and muscle relaxation. 6 to 12 weeks will make a big difference in most cases.