Breasts still high and tight 4 weeks post op. Is this normal?

Being patient is easier said than done, but
you should remember that the final results from breast augmentation can take up
to 6 months to develop. During this time a number of processes will take place:
swelling will dissipate, the implants will settle into the breast pocket, and
the skin will stretch to accommodate the implants. As with any procedure,
strict adherence to your surgeon’s post op instructions is key. If your surgeon
prescribed any massage exercises, be sure to do them regularly to help prevent
the development of scar tissue and help the implants settle into a more natural
position.

The final results are mostly present including "dropping of the implant" when implants are below the muscle within the first 3 months for most and certainly by a year. Breast implants initially after surgery when placed in a submuscular position often give superior fullness that corrects itself with time, the "fluff and drop" phenomena. In reality the pectoralis major muscle takes a while to adjust its size to accommodate the implant as well as occasional muscle spasm which keeps the implant projection higher than its final resting shape. As the muscle relaxes the projection of the implant often increases and the breast shape improves. Massage and use of a superior placed elastic strap can often make this process go faster.

 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 and 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. 

Again, best to follow your plastic surgeon for more specifics. Best wishes for an outcome that you will be pleased with long-term.