I've had fever blisters in the past. had a root canal a week and a half ago for dental abscess. now i woke up with fever blister. is this common?

Not uncommon: "fever blisters" or cold sores on the lips, are extremely common, and due to a type of herpes simplex virus (not genital herpes). When our immune system is down (as in during a cold or other infection/tooth abscess) or we are under a lot of stress (anxiety) then the virus can activate and form the blister.

Could be: Stress, like that form a root canal, has been known to cause "cold sores" to come out.