Do you smell actual fumes/gas in the cabin, as with your Mazda? Does your car still have 'new car smell'? Does your meter disclose levels of Formaldehyde and Total VOCs, or does it just indicate yes/no presence?
I guess I'm not convinced your car is fully off-gassed after a year on lot. Your car was "sealed" most of the time (and in steady-state/equilibrium?), assuming it wasn't test driven daily. Actively driving it (opening/closing doors and windows, running air/vents) is what would help purge things best... and that has just started for your car.
After a year of driving/ownership, my own car still has 'new car smell' - with glues, fabrics, plastics (dash, floor mats) and other surfaces still actively off-gassing. Some materials like carpeting off-gas VOCs for up to 5 years. And if the dealer cleaned/detailed the car before delivery, the after-effects of those cleaning sprays could still be on surfaces after use. If the meter only shows yes/no presence vs measured levels, it could detect trace amounts for years.
Worst case, if the EVAP system is at fault, there should be an electronic code of some sort that the dealer can find/diagnose. And the malfunction indicator lamp should come on if there's an issue with the emissions control system, which is checked as on board diagnostics at each start-up.
If you're concerned of issue, it's worth reporting and having the dealership check. Your car is still under standard 3 yr/36k warranty, and that warranty is extended to 15 yr/150k
for the "Evaporative and Refueling Emissions Controls System" if you're in one of the 13 states aligned with California Emissions Laws (CA, CT, DE, ME, MD, MA, NJ, NY, OR, PA, RI, VT, WA).