I don't think that they have changed, I think 455 and 457 have the same hoods.
I bought a pair of 452s maybe 7 years ago, neither had hoods. Wolverine was the warranty center for CZ at that time I thiink. I got them to order two from CZ in Europe. It took the best part of a year, but they did come in, and were about $5 each.Yes, The problem is I can't even find any hoods for 452, 455 or even the latest 457. They seem to be out of stock everywhere.