THe Explosive gas (Propane) alarm can be set off by many things. Not just propane but ANY explosive gas.. Methane, Butane, alcohol, gasoline vapor. Many cleaning products or spays.
Low battery voltage, though this may "Chirp" (or squeal)
Other 'Internal failure'.
You really need the fine manual to interpret the light.
NOTE: One thing you should NOT do... (True story, Neighbor of mine just now)
He came home after 22 hours to the alarm alarming.
Went in and found one knob on stove turned somewhat ON
Checked all knobs including the one that makes SPARKS (Ignitor knob)
BOOM.
Thankfully the mix was not ideal or he would have been seriously damaged, As it was he lost a bit or leg hair. and likely one pair or undies.