[Rinehart]

Yes, that seems a quite reasonable explanation--this had always been there, but it wasn't noticed until the rapid expansion of television after the war, and you feel that it was a good-faith error. According to the 1939 Broadcasting Yearbook, there were 23 licensed experimental stations as of November 1, 1938, some of which were in the large cities of the northeast, (7 altogether in NY, Philadelphia, Chicago, and LA,) and the rest scattered around the country, some of them in very unlikely places.
As of January 1946, there were 9 commercial stations and 26 experimental stations; by March 1947, 55 commercial and 63 experimental; by Jan 1948, 72 commercial and 91 experimental; at the time of the license freeze in September, 124 commercial stations (the Broadcasting Yearbook does not list experimental stations after the 1948 edition; all figures include construction permits granted.)
The FCC must have made an announcement on the subject, but when I looked through back issues of Billboard and Broadcasting Magazine I didn't see anything. If anyone knows where I might find it, please send me a PM.