Tony, since they were kicking them out at about 10,000 Lugers per month, I would say yours was completed in Jan 1942, as well
The earliest recorded double E/135 is S/N about 8500 no suffix and the latest is about 1000b.
My guess is that about 4000, 1941 frames were used in pistols completed in 1942. They were intermixed with 1942 frames!