Anyone know what could have caused this? I had Circuit City do the install, and a mile from the store the PSI warning light came on. I'll take it back tomorrow, but this was the first Z they had done work in so I would like to be able to point them in the right direction...or could it be caused by something simple I can fix?

The pressure readings on the display show normal psi #'s, but I have the light on the dash and a blinking PSI on the display.

edit: forum search shows this to be a common problem, I will top off the air tomorrow to make sure. Its been hot all day so not caused by low temps, timing stills seems odd that it went off as soon as I picked the car up.