It is difficult to speak intelligently on this design without seeing a schematic, but it is not at all unusual to have a low-inductance choke between the drain of the PA MOSFET and the supply, _if_ it is resonated against a parallel capacitor at the operating frequency to create a high impedance at the drain.  This capacitance may exist in parallel to the drain-source of the MOSFET, and have a return through a larger RF decoupling capacitor in parallel with the supply voltage.  The low value choke may let RF current pass, but as long as it is a high Q circuit, there is no RF power being dissipated.

73 Dave NM0S