People who actually watch plays would think the casting was normal on stage
so if you mean that you were "aware" that it was "odd" to mean that you "recognized that it was not normal," then you were actually wrong. The original version of Peter Pan, before the novel version existed, was a stage play in 1904 (I think the Mary Martin version is mostly that one with added songs but I'm not sure) and the major theatrical versions prior to the Mary Martin version had also cast women as Peter Pan. And casting actors as the opposite gender in one direction or the other is a totally normal theatrical practice that has always been around. But maybe you just meant that "present-day adults" are now uncomfortable with 1950s laxity toward gender bending?
I haven't actually seen it since I was a kid but the notions that adults wouldn't be expected to enjoy Peter Pan and that present-day people people wouldn't be expected accept women playing men the way that they did in the 1950s both seems ironic. I guess maybe the fact that it's a canned production might make it harder for people treat it as theater rather than a TV show.