Norm,
A -very- merry Christmas to you!
1900AE #13499 has three-digit numbers on small parts. Not unknown, it would be really interesting to know how common this really is. Also, I've never been sure about this, but I think you have to dismount the safety lever to see the number on the thumb safety on a commercial Luger.
I have no 1902AE Fat Barrels with proofs until about #23000. This is not definitive, of course. You didn't say what the serial# of your gun is
Can't wait until you start braggin'...
--Dwight