I also had a positive pet scan about 9 months after treatment ended, a reading a little above 3. My Oncologist said it could just be scar tissue. He sent me to the ENT doctor and for an MRI, neither showing anything. He then said it most likely nothing to be concerned about. Now, 6 months later I'm scheduled for follow up scans.

About your jogging, when I go for the PET scans, the technician always asks if I've exercised in the last 24 hours. Apparently, recent physical activity can have some effect on the results. Something to ask about.