Pre-regulator sizing
By selecting the correct current for the resistor and the Zener for the nominal operation (as you indicated in your text), everything works well, and the power dissipated by these two components can stay comfortably below 1/4 W. Depending on the Zener and resistor power rating, there is a lot of room between a resistor with a value sufficient to provide Zener regulation and value which reaches the power limit in any of these two components. Base current will not be too relevant since the load current is very low (for a low beta, e.g. 50, Ic = 30 mA -&gt; Ib = 600 uA).

But, as you can see @500 ms, when the output is shorted, the current through the resistor is increased (if the input voltage source is capable of providing the short circuit current). The power dissipated by the resistor reaches almost 1 W (beyond the plot scale).

The worst happens to the input BJT (again, if the input source is capable of providing the short circuit current). As the LM317 protects itself, the BJT becomes a soldering iron:

Edit: good to know your circuit is fulfilling your requirements. If the load regulation is affected by the shunt resistor, you may also consider a limitation before the BJT: