Pulmonary nodules are a common finding, particularly as you get older. I had one of those lung screening tests awhile back, that showed 3 small nodules. I had to have follow up CT exams @ 6, 12 and 24 months. No worries.

Your PET was likely a combination CT/PET, or they would have had difficulty determining size of the nodule, particularly at 9 mm. The fact that there was no uptake is the key.

They can check the nodules again, when they do your first post-treatment PET scan, which should be between 3 - 6 months after treatment. That is the best for these types of things, as if you had a CT alone, and it showed some growth, they would then send you for a PET anyway.

Good luck with the rest of the treatment, and don't sweat the nodules.