Shaylynn,
PET/CT dramtically improves the accuracy vs. a simple PET scan so that would explain how they have such precise data.

You MIGHT be having a recurrence so you may have radiation (& maybe adjunctive chemo as well) in your future to clean up the nodes and the original tumor bed. I'm not trying to scare you but tongue cancers tend to be aggressive. Because of your age they may have taken a less conservative approach. In any case, now is the time to have a complete medical team and have a consensual approach about all of your options from a tumor board. The cancer center should already have provision for this.

If you had a nodal involvement your TNM staging is probably not correct either. The "N" would have been a "1" anyway, since they found a positive node.