Was the SRW truck you were in a 2500 or 3500? I know in 08 the 2500 had TPMS but the 3500 did not - because of the gross weight.
If it doesn't give you the pressure accurately for each tire, it's a worthless system, IMHO. It's another electronic nanny that causes just as many problems as it solves.
So far I've had 2 false positive alarms with my TPMS - once while towing a heavy trailer and once while empty. Now I basically just ignore the TPMS light because I have zero faith that there's actually a problem. With my programmer I can just turn the system off.
I'm not sure how Dodge's system works, but the Subaru system has one receiver for all four sensors. Each sensor sends it's status, PSI, and serial number. The sensors are registered in order, LF, RF, RR, LR, so if you rotate your tires and don't re-register, then adjust pressures, you could set off your light.
I'm really not a fan of electronic nannies as I feel it makes people less aware of what they're doing behind the wheel.