I don't think it has to do with limited editions and stuff, otherwise I'm pretty sure the dealers would have known something about it and charged accordingly.
I'm pretty sure it's just a more modern production run where they decided to make them all with upswept beavertails . They could just have had issues with a machine and used another one instead to keep production going. I have a feeling they're all like that now.
I too go that surprise , the one in the window had the traditional one and was happy to have it like that.
EDIT: This is an old thread , but it seems there has always been confusion on beavertails for CZ's .. Here they say they never saw regular 75 with upswept beavertails, but things might have settled since then.
https://www.ar15.com/archive/topic.html?b=5&f=37&t=136924
