4 weeks PO my breast has had discharge. Should I be worried?

Did you have implants as well?
Is this discharge from the nipple or incision?
Does it a have an odor?
Is it white (pus-like), bloody, clear, or oily?
Is the skin black?
Do you have a fever or are the wound edges red?
All of these may be indicative of the underlying problem and may represent different causes.
Generally lactation occurs from the nipple with a clearing whitish drainage with minimal odor and frequently ocurs with placement of implants.
Please consult with your physician to evaluate other possible causes.

I fully agree with the other opinions given. You need to see your docor immediately for this. Your prognosis does also depend somewhat on the character of the drainage (e.g is it clear? red? foul-smelling? purulent?) Also - is the outer skin red at all? Signs such as these may indicate an infection or the presence of tissue that is not healthy inside of your breast (fat necrosis). Most likely, however, you have a fluid collection (seroma) which should be drained and followed closely afterwards. If your doctor is unwilling to see you or deal with this problem, then find another board certified plastic surgeon in your area who should be readily qualified to handle the situation appropriately and, just as important, provide the proper follow-up.