I wouldn't get hung up on upper (on the tube) vs. lower case (on the website) letters. The person(s) who put the info up on the site were probably just trying to get it done. 10-38 would typically mean Oct. 1938.
That date code page referenced is for Telefunken branded tubes.
The tubes can't be from 1938: The "Made in..." is in English. West Germany didn't exist yet.
I'm guessing these were made for Fisher, when they did tube gear (early 1960s).