I am looking for answers as to whether NaHCO3 buffered cell culture media stored outside a CO2 gassed atmosphere changes it's pH irreversibly.

I understand how the NaHCO3 buffer principally works. But I wonder if the equilibrium between CO2 and HCO3- is reversible, always readjusting, depending on ambient temperature and CO2 gassing (+ atmospheric pressure)?

Suppose I would prepare a medium that is NaHCO3 buffered and has a pH = 7.3 after preparation in the lab (i.e., 20° C & 0.04% CO2). The pH was adjusted using HCL and NaOH. If I were to incubate this medium for 24 hours at 5% CO2, 37°C, and then remove it from the incubator, would the pH then return to 7.3 at the Lab-atmosphere?

This would be easy to prove experimentally and I will try this out in the next few days, but I would be interested to know if I might be missing something.