Coughing up Tar??

Hey, I like to smoke cigs on weekends or when im stressed or at parties. At one period of time tho I was smoking Marlboro reds and I felt like I was getting addicted (i think they were just too strong) so I decided to quit smoking for like a week. After a couple of days of not smoking I started to cough and spit up what looked like tar because it was basically brownish black mucus...is this normal or just really fucking weird? Cause what I read was that smoking paralyzes the cillia in your lungs that clean out unwanted shit, and once they start working again it cleans out and makes u cough up the tar from smoking.