Some people get oral herpes as kids, from people kissing them, sharing toys when kids put everything in their mouths, etc., but since you haven't kissed anyone or shared utensils, if this is herpes, you've had it for awhile then.
There are also lots of other things it might be (an allergic reaction, cheilitis, Behcet's, a burn or other trauma to the area, etc.), so if it lingers or recurs, get it checked.
Did anyone kiss you? Have you ever had a cold sore before?
If you had no oral contact, you didn't get oral herpes from a dancer. If this is herpes, you either got it from kissing someone else, sharing drinks/utensils/etc., or you had it before.
Get it checked by a doctor to find out what it is for sure.