Magnetic Plug Torque

Hey,  I have the new model (Hex) magnetic plug on my 914.   I recently checked the mag plug with no issues and then went about re-torquing to the specified 18 ft lbs.   My magnetic plug has a black (plastic) washer that I can only assume was installed at the factory.  When I torqued to the specifed 18 ft lbs,  it felt as though I was crushing the plastic gasket and I stopped just short of the 18 ft lbs.

My question,  should this black plastic washer be there?   Does anyone also have this washer?

No washer.