Hi,
I found a data sheet that spec's the gate turn on threshold at 0.8v min to 3.0v max at drain current of 1ma. At the full current we might need 10v to drive the gate but since this is low current then we can probably get away with less.
At 4.5v gate to source i would expect the device to be able to pass 50ma, with 'on' resistance between 5 and 10 ohms. Voltage drop drain to source around 0.5 volts. A little less like 4.4v gate to source it is probably pretty close to that. As temperature increases it should be ok, but might have to be checked if the temperature is going to go lower than room temperature such as outside on a cold winter day.
But also i see the 1M resistor did not go lower yet. If this is only to be turned on once in a while then that might be ok, but the schematic says "PWM" which implies that it will be switching on and off. That means even 10k might be too high so this has to be looked at more carefully also.
Actually, 1M is so high that it may not even be enough to swamp out the collector leakage current of the bipolar so it might not allow the MOSFET to ever turn on.