Not the least bit surprising. I vaguely recall a similar situation when Windows XP came out. Adobe products are very tied to the OS and hardware platform. It's one of the few products where the cost reflects the investment and complexity of the product. We are after all talking about the leading design package that every designer that can afford it has.
I bought the Leopard upgrade the second it became available, but waited to buy a machine that (should have) had Leopard pre-loaded. I was somewhat mislead by the Apple reseller, because the machine in fact had Tiger, and I had to load Leopard. No great loss.