The thermocouple, located next to or just above the pilot light, generates the voltage to hold the gas solenoid open when it heats up. If the oven burner is igniting, the thermocouple is working well enough to open the gas valve. So if the burner stays on for a minute or two and then closes, I would think the thermocouple is probably working.
Is the burner flame full for the entire minute or two, or does it shrink. Shrinking would suggest a propane flow problem.