I had the same thing on my last PET--some "suspicous" uptake (ie. in the area of uptake that is "marginal" and is unclear whether it means something or not). The PET was done when I was about 20 months out from treatment. The ENT had me in for a thorough exam with the scope and they also did an MRI as followup. Nothing showed on the MRI or the exam.
The areas (all "Marginal") were on the BOT and two lymph nodes. And they were not there on the PET I had had 10 months before. However, about 4 weeks before the PET I had had surgery to remove the stent that was in my esophagus (long story why) and dilate my throat. As a result I was doing quite a bit more swallowing, which could have caused some BOT irritation and the glands could have been affected by the surgery. And of course they were using something with a camera to do that surgery and definitely would have noted anything they saw that looked like cancer.
It has left me a little anxious but last year when I was worried about my swallowing and looking for a surgeon to help me with a near complete esophageal strciture, I went through an ENT at Mass Eye and Ear and mentioned to him during my visit that I had had a clean PET a few months ago. He said, basically, that that was good but they didn't do PETS anymore at all there because they gave so many false positives (and this was with someone expert at reading H&N PETs).
So I think the best thing is to not worry too much right now. Though I have to admit, ever since that PET I had, I am a little worried about myself and it definitely put a damper on celebrating being two years out. I figure that if six months from that PET (which would be August) I still have no other signs of recurrence and still am getting clean exams otherwise, I can probably not worry about it.
Nelie