The air suspension light comes on when the air suspension control module detects a fault in the system. Because the car tilted back when the light came on, the fault is valid and not just a fluke.
Anything from a faulty ride height sensor, short/open in wiring, fault in vent solenoid, faulty compressor, or even a fault in the control module may be responsible. The only way to find out is to have the computer read with a diagnostic scanner that will read the stored trouble codes. At this point, you can decide whether to repair yourself or have a shop do the work.