I had a sore on my right upper lip three weeks ago, it was a canker sore, it cleared up about a week ago. Yesterday I took notice the same sore is starting to develope all over again. This time the sore doesn't hurt, not yet atleast. Is this normal?

Lots of times canker sores come back in the same place because they are viral........but set your mind at ease ...see a doc

Cold sores, canker sores and the various other names are all herpes simplex virus. It is with for the duration once you have it. It has a tendency to manifest itself, or become active, when you are under physical or emotional stress. One unusual thing about herpes is that it frequently is unilateral. Your body's nervous system, within which herpes likes to reside, is divided into left and right hemispheres. It will frequently only reside in one or the other. In my case I get a cold sore on the right corner of my mouth almost every fall, timed right after I get my annual case of the flu.... body under stress, immune system (puny as it is after all that it has been subjected to) tapped out after the battle with the flu virus. Every year it is in the same place on the same side.