I made the accident of performing unprotected oral sex and having protected vaginal sex with a one night stand with an unknown std status. I only licked her genital area 4-5 times before I stopped. She had no visible sores or blisters on her mouth or genital area that I could see. 

51 days after this experience after some slight oral trauma I started to develop what I thought were canker sores. There was a slight pain on the tip of my tongue where the trauma initially occurred that lasted 3-4 days and I developed three canker sores; two on the left side of my inner cheek/lip and 1 on the right side of my inner lip. These appeared to only be present on non keratinized mucosa. The sores were all round and oval shaped, had a red border with a white/gray middle and were all clearly defined. I did not notice any smaller clusters, blisters or oozing. The sores were painful from the beginning and resulted in a shooting pain inside my mouth whenever food directly touched them. The location of the sores were slightly raised and swollen. During this time I noticed my outer lips were dry and chapped a lot of the time. I was also feeling some general fatigue. 

After 9-10 days the sores went away. All the medical articles I’ve read have said canker sores are only present inside the mouth on non keratinized mucosa while oral herpes sores are only present outside the mouth. Is there a possibility that what I was experiencing was not canker sores but a herpes outbreak? Can herpes symptoms appear that long after a possible exposure?

Your sores sound very much like canker sores, as you expected.  Have you ever had a cold sore on your lip or in your nose previously?    i would not expect the very limited contact you had with her genitalia while giving oral sex would put you at risk of anything.  In addition, if you were to have symptoms with a new oral herpes infection, symptoms would appear within 2-14 days, at the outside, with the average being 5.5 days.  Your symptoms didn't show up until way later than that.  I would not have been worried about your having contracted an oral herpes infection from this contact.

Terri