Hi 4 week post gynecomastia and aerola reduction surgery, over time will the nipple size reduce as it heals?

Yes. your body does not know the difference between an operation by a surgeon and trauma (I.e. Getting a cut or other wound). Like a bruise, the operated area will swell and hurt for a while. Regardless, see your surgeon. He/she can make sure that there is no hematoma/serous (a fluid collection after operation). .