Strange that its first different but later the same.
Different temperature inside the tire, what you see on your TPMS , can be because of different load on R and L.
But that would not explain that it gets the same in the long run.
Mayby its because of the hot air from the exaustion pipe ( good word ???) that heatens one tire . Then at the long run the other gets the same by the more heat generated by more deflection because the load is higher there.
So yust some things to considder.
Normal inside tire temperature when driven for a while is about 112 degrees F/45dgr C. That is for passenger car tires, but probably also for LT . For ST it will get higher because of the more deflection such a tire has.
The heat is generated by the about 15 times a second deflecting an flexing back of every section of the sidewall. So more deflection generates more heat.
When braking or when one wheel stucks in some way, there is heat generated that is transported trough the rimms to the tires inside. It can rise the inside tire temperature to even 100dgr C/200dgrF? wich is boiling point of water.
The valves and the tires can stand this heat and the pressure rising that goes with it.
Can also be as simple as a little disfunction of one sensor.