Having just single boil does not indicate herpes. Oral herpes is usually caused by a virus called HSV1 and sometimes, HSV2. Its symptoms are burning, itching and tingling 2 days before lesions, rash around gums, mouth and lips, formation of several small blisters having yellowish fluid, these blisters can ooze, formation of yellow crust as healing starts and occasionally fever. If you are having such blisters then herpes is suspected. Otherwise it can be due to some other reasons not herpes.