Wikipedia:The flashpoint of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air. At this temperature the vapor may cease to burn when the source of ignition is removed. A slightly higher temperature, the fire point, is the temperature at which the vapor continues to burn after being ignited. Neither of these parameters are related to the temperatures of the ignition source or of the burning liquid, which are much higher.
Thhe flash point of propylene glycol is 210 F by the closed cup method and 224 F by the open cup method. You can hold a rod heated to 224 F near the surface of propylene glycol all day long without igniting it. The autoignition point is 700 F. If the glycol were to boil over onto a red hot heating element, there would certainly be a fire. If the vapor from glycol at its flashpoint overflowed the container, there might or might not be a fire, depending on the partial pressure of glycol at the hot surface, which would have to be at least at the autoignition point of the glycol.