I was at the dealership yesterday (for a couple of issues) when I overheard the service manager telling another customer "that light is always gonna come on (referring to the tire pressure light) - ide get worried when it never comes on or if it comes on and stays on"

I am a new owner but seems a little discerning when a "luxury vehicle" is supposed to continuously flash pressure warnings at you, anyone with similar experience?

 

The TPMS light will come on when the Tire Pressure drops below a threshold, and some will activate if the pressure is too high. Pressure is related to temperature. If the tires are set when warm, the pressure will drop when the tire cools over night. Some dealers will over-inflate to avoid this. Ideally, the pressure is set when the tire is cold. Hard to do when the customer has driven the car to you and cannot leave it overnight.

 

What he said.
And to add to that the TPS system is a generic system that Rover contracted with, the same system is probably used in BMW's and Nissan's.
Just because the car brand is "high end" does not mean all of the systems are.
How much load you have in the back will effect tire PSI too, towing a trailer, mother in law in the back seat...long highway drive in 100+F temps...
Also if you install a different tire than what the truck came with from the factory it can set off the light because a different tire will heat up/cool down at a different rate.
Lots of factors, TPS systems are junk and a huge waste of space.
But they are mandated by the National Traffic and Highway Safety Administration on all new cars now because of the Ford/Firestone crash problem from years ago, so all new cars, even the cheapest car you can buy have TPS systems.