You have had a wound separation which could be for several reasons. In addition to the saline gauze I might add Silvadene cream to speed healing and prevent infection.
Wound issues after reduction surgery
are very common. The vast majority heal with TLC and the concept to remember is moist wounds heal faster than dry, scabbed wounds. Ointments, Silvadene, saline all accomplish this so use what is recommended and convenient for you. And if things worse, please keep your surgeon informed.