Hello. There are a lot of changes the gums undergo during smoking especially if you are a chronic smoker. When you smoke, the harmful effects are masked and is not seen on the gums. when you stop smoking the effects are more visibly seen. During smoking the gums tend to be firm and does not show out the actual deterioration that has taken place.  When you stop smoking the effects are more visible and the gums show the signs of edema which is seen as red color in the gums. You need to visit your dentist for check up, so that gum condition is assessed and taken care of.