Low tire pressure indicator comes on and stays on

TPMS - Tire Pressure Monitoring System

I learnt a lot about the tire pressure monitoring system Nissan installs on their cars. Just so you know (like I found out), TPMSes are required by federal law. They engage when a car travels over either 16MPH or 25MPH, and measure against a factory-preset reference tire pressure at sea-level. If the system (which is embedded in the tires, and electronically sends a tire-pressure PSI reading back to the onboard chip) thinks your tire pressure is too low, it will indicate low pressure indicator on your dashboard.

The funny thing is that for the Nissan Rogue, the recommended PSI for all four tires is 33PSI. You can find your car's recommended tire PSI in a decal on the inside of the drivers car frame once you open the door. I have mine at 33 PSI, drove at 40MPH for 20 minutes, still nothing (indicator light doesnt switch off). Reading around the web, one problem people had was that the reference PSI (33PSI) is at sea-level and some folks were located at a place high above in the mountains. In such cases, you probably have to adjust your tire pressure to something different in order to offset the altitude. I am, sadly, at sea level.

Another possibility I read about was that Nissan dealers over-inflate the tire to about 38 PSI, and then you drive the car for a few miles over say 25MPH, the indicator goes off. At which point you deflate it back to factory-recommended 33PSI.

Finally, its always possible that my TPMS is messed up and isnt working right. This can often happen when non-factory aftermarket tires are installed. Getting those tires' TPMS hooked up to the computer is surprisingly expensive, apparently. So maybe thats the reason why I keep getting this indicator light.

So my choices are:
1) Take it to the dealer who might overinflate tires, run a few miles, and then deflate
2) Try 1) myself
3) Suspect that the TPMS is non-functional, have it changedhttp://www.blogger.com/img/blank.gif
4) Do nothing
5) Do nothing, but get a pressure measuring device and make sure im usually around 33PSI, and ignore the indicator.

The cheapest and least riskiest option in my view is 5), so thats what i did. I bought a quick-tire puncture fixing rubber sealant spray (you can simply spray right into the tire, the sealant will block up any puncture holes and let you drive a few miles to safety).
Heres the thing I bought: It came with a tire pressure measuring device. I keep it in my glove compartment and check before any long drives. Seems like my front left tire deflates faster than the right. I should probably get the integrity checked out soon. Still, some peace of mind until I figure out a good dealership to go to for repairs who isnt going to rip me off every which way....