Is Feeling Of Congestion In Chest Post Heart Bypass Surgery A Cause For Concern?

Hi, I had robotic heart bypass surgery 1 1/2 years ago. Since then i have been following my doctors orders for regular exercise and watching my diet especially salt and colesterol. Taking meds for high blood pressure, colesterol, and anxiety. I am a female 69 years old. Never had any serious health problems until this 91% blockage. Totally by surprise! My concern is that I have some congestion"like" feeling in my chest. No pain but I do have a little cough when I lie down. Is this anything to be concerned about? Otherwise I feel fine just a little tired. Thank you