Yes. All the time. Pet scans are very sensitive, and pick up all sorts of hypermetabolic activity, some physiologic, inflammation, from movement such as swallowing. The PET scan does seem early, but shown that it's 90 percent accurate by 8 weeks. Some doctors do scans 6-8 weeks for a number of reasons. Do you know the SUV for the highlighted areas.
If the doctor says to monitor, it sounds good.